Theresa got a 3DS for xmas and we have been playing the heck out of it. The 3D without glasses is crazy to see. At times when playing it becomes hard to hold the thing correctly to see the 3D. So for games like Mario Kart 7 it makes it easier to turn the 3D down, but in Mario land it is very impressive. That thing is going to get a lot of use.
Super Mario 3D land is a ton of fun. It is familiar, but they play around with the 3D all sorts of ways. I was laughing and the oohs and ahhhhs were constant. I am over half way done, but need to go back and collect a few more coins. The levels are pretty short and not all that difficult so you do not need to be a great player to have fun.