In general, I think that any way you can use to introduce reading will only help. My question is in regard to cost effectiveness. We have an older version of Leapster, with two of the books that go with it. I wouldn't have purchased it at the retail price, because that just seemed to expensive to me. However I found this one at a thrift shop for a couple of dollars. The children get it out about once a week and do the activities on it. That gives them just one more way to enjoy reading ... and there are many ways. So bottom line is it isn't going to hurt your child's learning, and may help. But, do you want to put your money into something like that or spend it on other items that may help as much or more?
I would also recommend that you look online for some sites that offer you online reading opportunities. Most of these cost an annual registration fee, but they also give you samples to look at free. Even having your child read those samples can be a good reading experience for him, and if you choose to pay the fee for the annual subscription, he'd have a lot of good reading activity online that would be quiet similar to the Leapster Tag books.