I just ordered Under Defeat myself. Never played the original, it better live up to the hype!
I just got done playing it a few hours ago. I really enjoy it so far. The mechanics make it very unique. I havent played a shmup like it before. You really depend on your option in this game, and there are many frantic moments where you want to shoot but you know you shouldn't because u have to charge up your option.
Also finding an option that you like is a lot of fun. On some stages i like the canon, and on other stages i like the rocket. So that makes the game play varied. Then there is the whole aiming mechanic that really makes you pay attention to how you are moving and shooting