Haven"t played it, but it looks to be a pretty fun game, despite the low DS graphics. I like how you can play with friends or even online multiplayer, something you don't see very often in LEGO Games. I also like how you can play with Mars Mission, Castle, and Pirates. You even get more hints about the stories of those themes!
Overall, seems to be a pretty good one, I would really like to play it if I could.