Good move towards introducing your kid to this great sport
If your son is going to use it for recreational, laid back play, it'll be fine. He may be outgunned by his friends who most likely have semi-automatics though. This can be discouraging for the new player, but if he's having fun there's no stopping it - it won't matter what he's using to play with.
I started out with a semi-automatic, which I believe everyone should, but shortly after I got the feel of the game and confidence in my abilities I moved to pump class and then to stock class.
Also, it's important to take into consideration safety. The MOST IMPORTANT piece of equipment in a paintball game is the MASK. If he's playing in the winter or cold weather, I recommend a dual pane lense, or "thermal lense" which helps prevent fogging. Don't skimp here - it's safer to not fog. I've almost been killed by a cactus because my lense was fogged beyond belief and I couldn't see where I was running
