I am not a hardcore Roguelike player, but I play lots of RPG and FPS games. So here are my advice:
1.Basically there isn't any story in this game. However, I have lots of fun to unlock those weapons, improve my talents, and enjoy the intense, tight gunfire experience.
2.Difficulty is fine. My attribtue is relatively low in early stages, but I feel much easier with improvement in talents and skills after a few rounds (maybe because I become more fammiliar of this game)
3.Hidden level is interesting with many traps. However, the jumping one is difficult and I can barely pass it within limited time to get the bonus.
4.I have very limited chance to reset the inscription of the gun, but a good inscription really helps a lot.
5.Sometimes the skill you can choose may be not the one you want.
Overall this is a pretty good Roguelike game with great potential, and I can play it for a long time.