I've been playing RE0 on normal and going through the game as a first experience (never played it before), and man, I have to rank it low among RE games. Possibly lowest of the old school style.
I love tank controls, but I feel like this game isn't built well with it in mind. So enemies like the bug things or the monkeys are annoying to fight. The leech zombie, while cool, is again just annoying and you just run by them and hope you don't get hit. In contrast, hunters are still cool.
Boss-wise, I don't think I've fought anything really interesting.
I don't like the item management and drop system. Since you have no idea what's coming up, I won't carry the grenade launcher or even the shotgun at times, which then involves an annoying amount of backtracking, as opposed to having a handy item chest nearby. The fact that they take 2 slots from 6 per person is also frustrating. Then you have the bloody hook gun.
I don't like the partner system either. Switching back and forth gets boring. Babysitting your partner who can get stuck or doesn't smartly avoid stuff is annoying. I think I've had to run through areas twice with both characters, one by one, just to avoid either getting hit. Then you have instances where the person with the shotgun/grenade launcher gets taken out, meaning you either suffer by running by stuff or reload the game with the future knowledge in mind. It doesn't help that I'm beginning to really hate co-op puzzles too.
Once I finish (probs about 80% done), I'm probably never playing it again.