All the negatives you posted are why Dark Souls fans (and now Bloodborne fans) love the game.
- You don't get xp, you get Blood Echoes. You can spend these to level up, buy equipment or other items and as part of upgrading your weapons. There's no level next to it, that's your insight. Insight is used to allow co-op play and also to progress the game at certain amounts (e.g after you gain your first insight you can upgrade at hunters dream)
- The story is all there to be seen, they just leave you to work it out. Between messages, cutscenes and dialogue you can get a pretty good idea of what's going on. There were communities obsessed with the lore of Dark Souls and Bloodborne is doing the same.
- The enemies you're referring to are hunter mobs. They supposedly hunted the werewolves etc. but got infested themselves. FOr a list of enemies see here - http://bloodborne.wiki.fextralife.com/Enemies
- The only numbers I can think of by enemies health bars are the damage numbers. They stack with multiple hits.
- Combat is great
- There are scraps of lore around, messages, cutscenes, dialogue etc. You'll get there