I bought, and beat Metal Gear Rising (when it was on sale a couple weeks ago for $15 U.S.). The game's much better than I thought it would be. From a gameplay standpoint, it's fun as heck, and Platinum did an excellent job at making combat that was extremely smooth. There are some rough edges, given the lack of development time, but those mostly show up in reused assets for the environments.
From a story standpoint the game was actually solid (and probably the best in the genre). I have to say I was impressed, especially given how much I (though not everyone) enjoyed the Metal Gear franchise. The game did a good job with some of its characters. The music and boss battles were the standouts, and the final boss is one of my favorites of all time. The perfect blend of absurdity (poking fun at Metal Gear, and the genre as a whole), and an epic and interesting fight. The music is also simply fantastic during all stages of the boss battle, finishing up with a song that really blew me away.
All things considered it's a really fun game for fans of the genre, or MGS fans, and I beat it twice (Hard and Very Hard) on fresh runs of both. The NG+ system is also excellent, allowing you to carry over your unlocks via level select, or start over with all your collectables intact, plus the two major story DLCs came free with the game. It's a short game if you just run through, but if you're like me, and listen to every codec call you can, it will last you twice as long (I got about 11 hours out of my first run, and 12 on my second due to dying a lot). Keeping with the trend of the genre, the game is very difficult.