I think people are being a bit unfair here. No, it's not the best in the series (I'd say the first one is, followed closely by the second). But I enjoyed it much more than I did the third one. I really really enjoyed the story, which I wasn't expecting at all; I was just expecting some fun acrobatics. The combat is fine. It's not incredibly difficult, and you can't really lose (at least, I didn't see a 'game over' screen when I played it). The art style is incredible and attractive. I think the cel shading works very well. Because of the lack of difficulty, it can be jarring to come into this game with the expectations of something like the first three games, but that doesn't make it a bad game. It's just a different direction. This would be a good game to introduce yourself to the series if you haven't played it before, to get yourself used to the mechanics and combat before jumping back and playing the earlier ones. Give it a (fair) shot.
I've sunk several handfuls of hours into this game over the last couple of weeks, and it's incredible. Not based too much on luck and not based too much on skill, meaning that, like Spelunky, when you finally break through and win, it's a magical run that sticks with you for a long time. Plus, there are a bunch of unlockable ships and ship layouts, so there's a pretty swell amount of replay value added to the already significant replay value that naturally comes with rogue-likes. Easily one of my favorite games of the year. Buy it.
