I got to see an early sneak peak of this (in 3-D no less!) and I thought that it was really pretty good. It's a really cute movie, and the ending is surprisingly touching - I was so surprised by how everything came back around and tied together. (I may have "awwwwed" quite a bit, as well.) The characters are, as you might expect, very bright and colorful (both literally and figuratively), and they're pretty funny. The Robinson family is a little bit strange, but charmingly so. The best part for me, hands down, was Bowler Hat Guy who is just fabulous (I wish he could have been in more of the movie, because I loved watching that character.)
I hadn't seen a 3-D movie in a really long time, but that part was fun. I mean, 3-D glasses pretty much can't be beat anyway. But, the 3-D didn't feel "gimmicky" to me, if you know what I mean, it wasn't, like, oh look we're putting this in 3-D because we can - I thought it worked really well with the animation, and added a lot of depth to it (at points it felt like your seats were in the Robinsons yard).
In short: I really liked it.
