Atelier Lydie & Suelle is the last game in the Mysterious trilogy of the Atelier series. It revolves around twins who want to grow up and be the top alchemy shop in the town/country. For the most part, the game is fairly decent for an Atelier game but lacks compared to previous trilogies in my opinion. Despite that, I feel it's the best game in the Mysterious trilogy and decent as an RPG in general.
The story for the most part is straight forward and simple, like pretty much every other Atelier game. You own an Atelier shop, but it isn't really treated like a 'shop' in such a way like a store or general request shop. One say I hope they add that into the gameplay, but I doubt they will unfortunately. The pacing of the story is still lacking compared to past Atelier games that had time limits in place. On the other hand it's a lot better than it was in the previous two Mysterious games.
I was a bit disappointed with how much time I had to waste getting the 'true' ending after meeting all of the basic requirements. I was forced to constantly make items, view scenes and then repeat over and over until I had all of the scenes finally viewed. It took a ridiculous amount of time, which was rather annoying. They really need to cut the useless crafting time to trigger the next events despite meeting all the other requirements. Battling may also work, but would probably take considerably more time. At that point in the game, I just wanted to finish since there was no post-game story content.
Characters on the other hand are mostly returnees from previous games in the trilogy. The new characters introduced are a mixed bag. Lucia and your father, Roger, are absolutely terribly written. I just want to make it clear that Roger is quite possibly the
worst character in the Atelier series without question. Mathias isn't much better than Lucia either. Then you have their character events that take place throughout the game. All of the returning characters get their story arcs complete, but I was rather unsatisfied with Cornelia's conclusion. I think they could have done a bit more on the players side, such as being able to visit another town or the conclusion itself. Otherwise they were at the very least decent in general. Pamela is also back to her old pre-Mysterious trilogy self, which was great.
The main characters were pretty good. Lydie and Suelle play off of each other fairly well and it's incorporated into most of the scenes without much fault. It was also nice to see someone like Suelle for a change who isn't the overly positive main character and is rather snarky. Although while I did enjoy them, I feel like they were lacking a little compared to say, Totori or Meruru. It might just be my memory remembering things from those past games more favorably as I can't quite put my finger on why I feel this way. Regardless they were still quite enjoyable despite their naive way of thinking that is prevalent in Atelier games in general.
Zones/Maps have improved significantly over Firis. While Firis was more about open exploration, everything was unnecessarily big and empty with a lack of faster travel for far too long. In Lydie and Suelle they have well populated areas with flora that aren't too big but there are able couple places, like The Frozen Palace, that are too damned big. Seriously,

that place. It makes moving to the objective take way too long. Since you don't really have any way to speed up movement and the shortcuts aren't particularly good, you will spend a lot of time running to a specific area (often the last area) of a zone. If they had a way to teleport to a specific map in a zone, then this wouldn't be such an issue. That or give you a craftable exploration item that improves movement speed.
Alchemy and the recipe system is better and less of an annoyance compared to Sophie and Firis as well. With Sophie, I hated the changes to the alchemy system and Firis improved it a little but still made it rather annoying. However now I feel like it's more on par with older games in the series without being too much of a drag while still keeping a fair bit of strategy in order to get exactly what you want for more complex traits and effects. The recipe system on the other hand has improved from the past two games. It's a better mix of discovery and books/events to acquire recipes. Unlocking a new recipe via discovery is not really an issue like the past two games either where it took a considerable effort to unlock stuff that was accessible at the time on your first playthrough.
Battle isn't that much different than past games, but will rely more on items this time around. Since there's no time limits in place, replacing items until you unlock item replenishment isn't a big deal. Though it is a little tedious in my opinion. You're limited to three characters in battle, all of which are alchemists except for one. Everybody can use items, but some are limited to attack or defense only items. Like previous games when the enemy attacks the main character(s), you can defend with one of the other frontline party members. What's interesting about it though is that early on you've got Suelle and Lydie both in the front, so when an enemy uses an AoE attack that hits everybody, you can use the third character and prevent both Lydie and Suelle from receiving damage.
You've also got support characters in the backlines that can't take damage but assist when you perform certain attacks. Suelle can use 'upgraded' items which is insanely powerful and Firis is really strong when using elemental items where she throws in up to three extra attacks that are quite strong too. However everybody else is far less useful as a support character, so you typically put Mathias in the back as the third that way the three frontline characters can all use attack items. It would've been nice if there was a little more variety to allow other people to be in other roles. I've heard the DLC characters are stupidly powerful, so that would change that. However they're like $10 a piece if they release the same price as JP PSN, which is ridiculous.
In conclusion, the game is quite relaxing and has done well to reel itself back from the past two games being less on par with previous Atelier games. However it still has a bit to go for it to be fully back on track since they started the Mysterious series. Hopefully we see the next iteration continue the upward trend that Lydie & Suelle has started. Oh and please don't do the whole 'ingredients talk to me' thing again. It doesn't fit into the game side of things at all and makes it feel very disconnected from the narrative.
So I can recommend getting this game, but your mileage will vary depending on how much you've enjoyed past Atelier games. It won't do much to reel in previous people who have come to dislike the series, but it's still quite relaxing for a game in general. If you're on the fence, then $30-40 isn't a bad price point when it reaches it. However keep in mind that it does have more faults than the games from the Dusk and Arland trilogies.