[quote name='matto1233']I'm excited, but I still have too many question before I preorder this, especially with L.A. Noire coming out just a week later. What is the leveling system? What does it get you? Will people ever be online? Is it impossible to complete single player?[/QUOTE]
Somewhat general questions, but I'll try...
1: Everything you do awards XP. You can have up to 10 characters. Each separate character is differed mostly by body type, which is not changeable (AFAIK), hence reason for 10 characters. Doing tutorials, challenges, leveling, and other methods unlock things for your character. Things like apparel, looks, tattoos, guns, weapon modifications, and possibly more.
Three body types (Light, Medium, Heavy). Affects how much health and maneuverability (parkour) you have. You can have any class and perk combination with any body type, but body type restricts your weapon selection.
Four classes (Operative, Soldier, Medic, Engineer), mostly differing in abilities. You level and gain ability points, which allow you to buy abilities for that character. I believe you can respec later, but you're still stuck with that body type, so it's beneficial to have different characters. Abilities can drastically affect how you play compared to others of similar role.
2: Of course people will be online! It's a shooter!
(see: #3)
3: It is not impossible to beat the campaign in single player. It's all pretty much melded.
You can start a game with all bots (up to 16 total players, with all bots but you), and have it open to the public. Or private (invite friends only). Or have no bots, but you'd probably have to have other people with you. You can play campaign or individual levels. Campaigns rely on the host for determining what map is next.
Or you can jump into someone else' game, instead of starting your own.
The bots are supposedly pretty good/fairly human-like. Hope this is the case, as I can't stand playing with most of the XBL cesspool.
Also, all XP gained in SP is counted. It's no different from playing online. There used to be an XP penalty for playing by yourself, but not the case anymore. Boosting is also unnecessary as you get put into different brackets based on your level. EX: Levels 0-4 are bracket 1, levels 5-8 (rough guess) bracket 2... etc. up to level 20, which is its own bracket.
Higher levels can enter lower brackets, but cannot use anything that isn't unlocked within that bracket. Low levels can enter higher brackets at will, but they will be at a disadvantage with unlocks.
Since I already have a bunch of info, I'll tack on some more...
Kill/Death ratio is not shown anywhere, as far as I know. At least not easily accessible. This is to reduce the elitist douchebaggery
"MY KD IS BETTER THAN YOURS LOLOLOL FAIL", since it is, again, a team-based game.
10 maps. 8 default, two unlockable (one per side, beating each campaign).
The preorder bonuses for
weapons are just skins. Don't get the wrong impression. They are not preorder specific weapon unlocks. Just skins. I believe the helmets are unique, though. Perhaps the attachments and tattoos, as well.
Can't think of much else right now... I kinda paced myself on Brink info as I've been looking forward to it for the past year. Hope this helped. >_>