A.F.
My mom just got my boys (4 and almost 3) the Leapster2 and they love them! I can't really say anything on the V-Motion (wanted to get it last year for Christmas, but never had enough money for it) or the Explorer (My mom wanted to get that one, but didn't quite have enough for 2 of them) as we have never tried them. But as for the Leapster2, they are a bit big, but they just sit on the floor or couch and play. It's pretty easy for them to use, we've only had them for about 2 weeks now and they already know how to do it themselves! They still come to me sometimes and ask for help, but they pretty much do it on their own. The come with "Creativity Castle", which is for drawing/coloring, and one game download from the website. (They have 4 starter games to choose from) For my 2yo (he'll be 3 in Dec.) I got him the shapes game and he does just fine with it! He was frustrated at first, but then again..he gets frustrated easily, but now that he's use to it he does fine. For my 4yo I got him the dragon one that teaches numbers and letters, he seems to be doing pretty good with it. I think you're son will be fine. Just get him something you think he would be interested in and that he needs to work on. (for example my 2yo needed to learn shapes and my 4yo needed to get his numbers and letters down for when he starts school)
And don't worry about all that "don't let your kid(s) play video games or watch TV" crud. I don't believe in that. I think as long as it's educational and you limit/monitor them, kids will be just fine. I mean all of us turned out just fine, and I'm pretty sure just about everyone on here watched lots of TV when they were kids. lol
Hope this helps! Good luck and have fun! :D