In your case, I might avoid Universal until he is a little older and can handle rides at Disney like Star Tours, Dinosaur, Tower of Terror, etc.
Universal is more of a teen/adult park compared to a child park. Sure there are a few things for him to do, but not enough, imo, for the price to get into the park.
A quick run down of the rides for you to decide if Universal is right for him:
Shrek 4D--A movie where the seats move back and forth and shake around. Also, you get wet and get air shot at you. Also in 3D.
Hollywood Rip Ride Rockit--Roller coaster
Twister--A live, short standing show where you watch a twister come. It is like a scene out of the movies featuring high winds, water, fire, loud noises, and a sudden floor shake at the end.
Mummy--Roller Coaster
Disaster--You ride in a big subway car that stops at a subway station when an earthquake happens. The car rocks, lots of loud noises, fire, water
Men in Black--Similar to Buzz Lightyear, except your car will spin from time to time. Same concept as Buzz however. You get a gun and get to shoot aliens.
Simpsons--Like Star Tours at Disney
ET--like Peter Pan at disney. The car follows a track that has some hills in it! However, just like peter pan, it does not go through the hills fast. It mantains the same speed for most of the ride. Very family friendly.
Terminator--a 3D movie (that runs about 20 minutes long, very cool show) that features a lot of fog, live action, gun, etc.
Horror Make up show--avoid! I am 22, not afaird to ride any type of ride, but horror scares me to death and avoid this show all the time. Saw it once and hated it.
At Islands of Adventure:
Hulk--Avoid
Storm Force--like the tea cups
Dr. Doom--Like Tower of Terror
Spiderman--a motion simulator like Star Tours, on a FLAT ride track that moves through a building. The motion of the car, and the video on the screen simulates flying through the sky and free falling. Also features loud noises, fire, and water. The ride is also in 3D.
Popeye--A family style boat ride like Kali River Rapids at Animal Kingdom. Has hills, so avoid.
Dudley Do Right--Like Splash Mountain, again, has hills, so avoid.
Jurrasic Park River Adventure--More intense version of Splash Mountain with a massive hill. Avoid.
Harry Potter FJ--Similer to Spiderman, except your car moves around a lot more. Lots of dark, loud, intense moments.
Flight of the Hippogryph (SP?)--a "kiddy" roller coaster, but from the sounds of it, avoid since it has hills.
Dragon Challenge--rollcer coaster
8th Voyage of Sinbad--a live action show featuring lots of pyro and water. Very cool show, but very loud at the end.
Posideon's Fury--a walking tour/show. The last room features fire, water, bright lights, and loud noises.
High in the Sky Seuss Trolly Ride--A slow moving ride around the Suess land. Should have no problems with this one.
One fish, Two fish, Red fish, Blue fish--Like Dumbo
Cat in the Hat--like all the other rides in Fantasy Land at Disney, except this one spins around to point you in the area that you need to be looking at.
There are a few I left off, but as you can tell from this list, there is not a whole lot to do for a kid that does not like Pirates. Like I said at the start of this post, I would wait a few more years until he can handle some bigger rides at Disney.