Totes finished this game a week or so back. Been playing it with a friend co-op, so I haven't done Ada's yet. Waiting on the co-op DLC for that.
Best campaign: Leon & Helena. I just loved the environments and enemies of the campaign much more than in the other two. There are also a lot of great nods to RE2, especially a great tongue-in-cheek one at the end of the first chapter. My fav moment is during the end of the campaign when Helena up-front asks Leon,
"You have feelings for Ada, don't you?" And I just wanted to high five her, because Leon totes wants to toss Ada his rocket launcher. I ended up really liking Helena, and I hope she returns in future games.
Jake and Sherry are a close second, since I think their chapters have the greatest mix of game play; from exploration, to puzzle solving, to stealth, to combat (both melee and firearms).
Chris and Piers' campaign has some problems, but those have already been mentioned in this thread. However they get an award for (End of Campaign Spoilers)
Best almost kiss.
Gameplay wise the controls were a bit wonky at first, but hey, it's Resident Evil! While they took some getting used to, I don't think they're bad, they just a bit of a minor learning curve. The last third person shooter I played was Mass Effect 3, and I kept trying to emulate its cover mechanics, and always ended up leaping over the cover. I love the herb system in this game, and I hope they keep it.
All in all I'm quite satisfied. Can't wait to do Ada's campaign and to see what else they're coming up with DLC wise. While I think it may be unlikely, I'd LOVE to see additional DLC campaigns for other RE characters, like Jill or Claire.