For Christmas 2 years ago (the year it came out), we bought my daughter the Vsmile handheld. She loved it. Right after Christmas, the Leapster went on clearance at our local Sam's Club. It was $30 including 2 games for it. Needless to say, she got that as well. Later, it came down to $15 so my then 1 year old son got one as well (his came with different games; I couldn't have purchased the two games alone for $15). My kids loved both. The nice thing about the Leapster is that it has a stylus which allows it do have games that include drawing and/or writing. The Vsmile doesn't have this. However, the Vsmile uses the same games for the handheld that it uses for the regular Vsmile which is a bonus for it. If you don't mind purchasing a bunch of new games, then I would go with the Leapster since it has the drawing/writing as well. Honestly, they are pretty comparable. In fact, some of the games are quite similar. They both have Thomas the Tank Games and Cars games, for instance. If it was me, I would probably buy the Vsmile handheld and add to his game collection. It would give him a lot more choices in games to play.
Please feel free to email me if you have any specific questions about either one.