I actually own both. I bought the iPad2 first then the Galaxy Tab 2 a couple weeks later. I actually like both devices. Each one has its plusses and minuses. If I could combine both the result would be the perfect tablet.
I would recommend the iPad for most people that want to play games and consume media from iTunes, because there is a seemingly unlimited selection of apps/games and synching from iTunes is a no brainer. The overall experience with the iPad is polished as you would expect from Apple. The hardware is first rate and the update to iOS5 is going to be excellent (I'm typing this on the split keyboard).
The GT is my toy that appeals to the hacker side of my brain. I am already rooted and running an overclocking kernel. I uploaded all my music to Google's cloud service so I just stream my music to the GT. I prefer the Honeycomb browser since I do frequent sites with embedded flash. The display is a touch nicer than the iPad's with a little more brightness and color saturation. The added resolution is nice for surfing. The GT is rough around the edges. There is some keyboard lag especially with the stock keyboard, apps crash occasionally, and there are only a couple hundred Android tablet apps vs. over one hundred thousand iPad apps. The GT is lighter and thinner than the iPad, but it is really insignificant so the point is mute.
So for your son it really comes down to his preference. If he wants apps, games, and a tablet that just works I would recommend the iPad. If he likes to tinker, hack, and struggle at times 🙂 I would recommend the GT2. Or you can buy both and just trade off every week 😀