One of the best surprises of 2012. The atmosphere is incredible, and the music is magnificent. The game's difficulty may be a little high, but this is also another reason why I love this game. It reminds me of good hard arcade games of old. You need very fast reflexes - decisions are made in less than a second, else you're dead. You hesitate half a second between killings, and you end up soiling the floor with your blood.
One negative point: no vsync.

Don't judge a book by its cover. This little gem is one of the best strategy games I've ever played! I especially love the lack of eye-candy, which in this kind of games is just a distraction.
Many campaign options and modding capabilities extend the game's longevity, and replayability is assured.
Frame rate slows down at times in big cities, but that's not too bothersome.

I wasn't so hooked to a shoot'em up since, like, many years? Keep in mind that I never liked bullet hell shooters, I'm more of a "classic" oldschool shooter fan. And I don't like vertical scrollers with horizontal orientation either. In fact I actually bought this game mainly to support the makers, I thought I'd never play it much.
Was I so wrong!
This game is really something special -- the unlockables keep you coming back for another play; the soundtrack is engrossing and beautiful; the graphic style is wonderful; the gameplay mechanics quite simple; the boss battles are extremely enjoyable.
I even played it with the keyboard before I managed to get hold on my old arcade stick. Keyboard play is feasible, although the Divine difficulty level proves to be unmanageable without an arcade stick. I can fare better with a keyboard than a joypad anyway.
One thing missing is some scanlines graphic options which would improve the visual quality.