Bioshock 2 ruined the series for me and I can't for the life of me recall why.
Try it again then. If you have enjoyed the original, chances are you just were in a bad mood. There's no way you'd enjoy original Bioshock and not the second game, as they're essentially the same.
Infinite, while a big improvement in terms of gameplay, bores me to tears. I have no idea why though.
I'll tell you why: It's not
a big improvement in terms of gameplay. Not at all. The gameplay is just flatout boring. I'm going to give you a little scenario here:
Bioshock - you see a room. You sneak your way to a camera, you hack it, turning it friendly, and then you lure splicers in its general direction, letting bots do the work for you.
You see a camera, you use the security plasmid on splicers to turn it against them without hacking.
You bypass the camera altogether and use enrage to make the splicers fight amongst each other.
Add to that that all levels are fairly open, you can freely combine weapons and plasmids, and you get a game with tons of options for any given situation.
Bioshock 2 is the same thing, except it gives you even more options - you can summon a security drone, you can send an invisible scout to hack equipment behind your enemy's back, you can heal using upgraded decoy plasmid. Or you can use the drill's dash to obliterate everything in your path if you have grabbed your upgrades properly :-P
Now, Bioshock Infinite stripped most of that out. There's no hacking, just a variation of the enrage plasmid, it only limits you to two weapons and one ammo type, combat zones are extremely linear and the only bits which are genuinely interesting are the ones with those rail ... Things which give a combat great dynamics, but those are at about 1/5th of combat zones. To the lack of options add the fact that the weapons feel terrible, there are no actually interesting weapons at all (you can mostly choose between slow firing rate + high damage, fast firing rate + low damage, shotgun and grenade launcher. That's all there is.) And the game treats enemies as zerg rush, throwing loads and loads of them at you - feels more like Modern Warfare than anything else, thank god for the more open non-combat areas.