With the recent price reduction to 400 MP, this game is well worth that deal, with very nice looking graphics, I would say the best for a XNA game so far.
You can definitely spend a few hours within this game, with challenges to complete, to unlock weapons, characters etc.
The script also seems well polished & funny at times :) The controls are unique/ish but are similar to that of Too Human (poor game), but with the right analog stick being used to control your weapon.
This game has the professional feel, that many XNA games lack, which makes it well worth the price for 400mp, With each level being able to play on Easy, Medium & Hard. You will keep coming back for more, to beat the boss and become the ultimate champion :)