Fun for a few minutes...
My impression is that games of age, like Crystal Quest and Robotron, still feel like games of age, even with HD graphics. I would like to see the developers change the game play up just a little bit, to adapt to the changed gaming environment. Add weapon upgrades, speed bursts, invinciblity items.
Bottom line: For 400 Marketplace points, it is worth a look at, but if you have not really thought about getting yet, then you could pass this one up and wait for something better. Microsoft has commented recently, that they will be pushing a lot of development in the marketplace and Arcade specifically, so there will be plenty more games to choose from in the very near future! I can't wait!