Great game. Loved it from beginning to end. PSNP guide listed it at a 15-hour plat but that's rushing through and not doing anything aside from targeting the trophies. I'd estimate I was closer to 30-35 at the end (hard to tell as the game has the same bug Rogue Legacy did--putting it in rest mode doesn't stop the clock.)
S&S definitely has Dark Souls influences, but it's got a lot of Metroidvania to it as well. There's shortcuts all over the place, hidden doors, solid platforming elements, and areas/chests/enemies you can't get to until you've gotten further in the game and unlocked special abilities for. There's not a lot of special abilities, but there's a gravity flip, wall jump, double-dash in the air, the ability to solidify moonlight into platforms, and an ability to turn other barriers intangible so you can get through them. If you liked Dust as a combat platformer you should definitely like S&S.
The name comes from two game elements; salt is the main currency in the game. It's what you use to level up your character, upgrade your gear, and transform your gear into stronger weapons and armor. Just like in the Souls game, if you die you lose all your salt and have a chance to get it back by either killing the monster that killed you or (if you died from falling) by killing an easy monster that spawns where you died. If you die before getting it back your salt is gone forever.
The other game element is the sanctuaries that are scattered around the map. Sanctuaries are a replacement for bonfires from the Souls game, but with a bit extra added. Sanctuaries are either uninhabited when you get there, at which point you can claim them, or they're inhabited by one of seven religious sects you can join. When a sanctuary belongs to your sect you can make an offering to the sanctuary which prompts various people to show up. Leader, cleric, blacksmith, alchemist, buyer, guide, etc.. Each sanctuary can home four of those people, each of which provides bonuses while you're in the sanctuary area. Blacksmith causes your attack to go up, the guide causes enemies to drop more items, etc.. Space is limited and the offerings are drop items, so there's some decision-making around where you want to put people. In addition to the people above, visiting a sanctuary lets you level up, allocate skill points, and refills all your refillable potions.
Shrines can be found shortly before every boss. They don't provide the full benefits of a sanctuary but do trigger an autosave and refill your health and potions.
Transportation in the game is very easy. The sanctuary guides allow free warping to any other sanctuary. Generally you'll want to put a guide at every location if you can. When you're out in the field you can use a Bell of Return, which takes you to your last sanctuary or shrine visited. Alternatively you can use a Calling Horn, which lets you warp to any sanctuary you have a guide at.
The skill tree in S&S follows the same approach as Final Fantasy X; you have a large number of attribute nodes that you can spend points on in order to navigate the tree to particular skills you want. If you want to use greatswords, for example, you'd look at the path between your closest current skill and Class 1 Greatswords in order to figure out the best way to get there. Here's a picture showing part of it:
Because of the above approach your starting class doesn't really matter. You can make any combination of skills you want--focus on magic and using a mace, focus on daggers and prayers, etc.. One thing to keep in mind is that not all stats have a global impact on your character; strength, dexterity, magic, and wisdom do absolutely nothing unless you're using a weapon or magic or prayers that scale with that attribute. Putting points into dexterity is pointless if you're using a greatsword (their damage scales with strength.) Changing your mind about your build partway through means you wasted any effort you put into nodes that don't suit the new build.
The only two attributes that are helpful no matter which class you choose are endurance and willpower. Endurance determines how much you can carry; the game has roll speed breakdowns at 25% load, 50% load, 75% load, and 100+%. I'd recommend not going over 50%; I used 50% and a ring that increased roll speed to good effect. Willpower adds stamina (jumping, rolling, swinging a weapon, and using magic/prayers all pull stamina temporarily) and focus (which is what spells and prayers pull from--the MP bar, basically.)
An additional thing to keep in mind about the game is wounding and fatigue. As you take damage your maximum health bar decreases. Depending on the amount and type of damage this can be a small or large decrease. Fire damage, for example, can have a big impact; if you've not visited a shrine or sanctuary in quite a while it's possible for your maximum health to drop to 50% or even below. Health potions won't do anything about that. There are prayers (cleric spells) that can restore wounding damage, though. Fatigue has a similar effect for stamina; every time you jump, cast a spell, etc., there's a hit. The hit varies per action, but generally spells are the big culprit here. There are items you can get from your sect that restore fatigue--they can't be purchased, but when you increase your devotion level at the sect you can choose a reward, one of which is a bottle of the fatigue potion which then gets refilled at every sanctuary or shrine. At the end I was getting three of these since they're pretty useful.
Equipment in the game doesn't work the way I expected it to. You don't get huge upgrades by getting further into the game and picking up dropped loot. Pretty much all the gear you can find sucks. What you do instead is offer the appropriate stone to a sanctuary so that a blacksmith shows up and then have him upgrade your armor and weapons. The first 4-5 upgrades are pretty cheap, salt-wise, and require items that are quite common. As you get further into the game and kill higher level enemies and bosses you'll pick up upgrade items that can be used to get your gear to higher levels or transform it into better items.
Overall the game wasn't that difficult. Various enemies were a pain in the ass, particularly the ones that used magic but those were less common. Bosses either took me ~5 tries or I knocked them out on the first run; if they took multiple tries then on subsequent runs I'd adjust my approach; switch from sword to hammer (enemies can resist slash or impact damage, but generally not both), add a ring that increases defense against fire or lightning or whatever. None of the bosses have particularly difficult patterns but if you're weak to their attack they can one-shot you. Sometimes the boss would cause a lot of wounding, though, and I'd end up with a low health bar maximum and I'd be scrambling to cast Cleansing Linens to get my maximum health back up. The bosses are going to make you think about your approach but are not hard as long as you adjust appropriately. Since there's a shrine right before each boss it's generally not a big deal to take a few runs at it; if you lose your salt to a boss you don't even need to kill it to get the salt back, just reduce it's health by about a third and it'll be restored.
So...great game...but not perfect. Weapon types aren't balanced well. Great swords are the best weapons by far; go for those and great hammers (for enemies resistant to slash attacks--armored knights for example) and you're good to go. Both item types scale with strength, so you can switch between them to great effect. Magic is supposed to be even better, but I didn't use that so I can't speak for sure on it. Gold is fairly worthless in the game; there are items you can buy like the above-mentioned Bell of Return or the Calling Horn, but those are cheap. The only thing I recall costing much was higher-level spells, which ran around 5000 gold. I had well over 100k at the end. You can spend money to buy salt bags, too, so that's a decent place to dump it. Resting your PS4 messes up the game time as mentioned above. I did have the game crash twice when saving, which were "Oh, shit!" moments but the save was fine; people online have also commented on this, but both times it happened to me were one after the other so I'm not sure if there was something about that location causing the issue.
The game trophies are great. Just about every trophy is for beating a boss. The exceptions are for joining each sect (there are seven sects), maximizing your devotion at a sect (turning in seven sets of 3 items to the leader, which each gives you reward like the fatigue potion mentioned above), upgrading a weapon to the maximum, and completing a set of interactions with three NPCs. Oh, and there's two different endings each of which has a trophy, so just back up your save at the last boss, knock him out for one ending, restore the save and repeat for the other ending.
For the sects trophies; each sect has seven levels of devotion; you level up by collecting sets of three enemy trophies (ears!) for the sect leader. This takes you from the beginning to the end of the game, but joining another sect makes you leave the first sect and kills your progress towards the devotion trophy. There's an easy workaround; the game auto-saves when you kneel at a sanctuary, but after the auto-save you get the options to gain a level, use your skill points, or take an oath. What you can do is kneel, wait for the auto-save symbol to disappear, then take the oath. This will trigger the sect switch, you'll get the trophy, and then you close out of S&S and re-open it at the last auto-save (before you took the oath.) It's an easy workaround; just don't kneel again after switching sects!
If anybody's curious; my build was two-handed hammers level 4, light armor level 4, great swords level 3, prayer level 3. I initially went for heavy armor but it wasn't worth the slow roll and I recommend staying away from that.