Here are some first impressions of Super Mario Galaxy 2 from Gamespot UK:

The first level we saw was set in outer space, with several brown mounds of smaller planets that can be accessed by warp stars. By holding the circular red drill over his head, Mario is able to dig through the planet and pop up on the other side. Using this new skill, our favorite plumber is able to reach platforms that are otherwise inaccessible by conventional jumping methods. We also watched as Mario was able to drill inside a hollow planet and collect a ring of coins within. Like the last game, part of the appeal is finding out how each planet works as they all have their own unique set of rules.