I preordered Rogue Legacy ($10), which has a demo as part of the preorder. Overall, I was pretty impressed.
The mechanics are very similar to Symphony of the Night, and they were pretty solid on a 360 controller, which the game supports natively (pretty sure it's an XNA game). Controls are simple, although you can expand them later with upgrades to your character. The difficulty is hard-ish, although you get upgrades that make it easier. I still died a lot. The game definitely has some shmup type elements to it.
The music and art are pretty good, but nothing stands out in particular. In those respects, it's in line with some of the better flash games. Although it has a lot more depth than a typical flash game.
You can upgrade your character's stats, unlock new classes, and find equipment and other blueprints.
There is a bit of humor, some subtle, such as displaying the word "balding" instead of "building" if your character is bald when the castle is generated, and some not so subtle, such as failed jumps/fart noises if your character has IBS.
The trait system is neat, but I died so many times that I cycled through all of the beginning traits rather quickly. I imagine there are probably more, but I don't know for sure.
Overall, if you like Metroidvanias, challenging platformers, and games with progression systems, I highly recommend it. I definitely feel that I will get $10 worth of gaming.