Nope. Should be interesting. We've been a Disney family pretty much, with the occasional visit to some of the smaller parks like Dollywood. Never Universal though.
Well, it's a very interesting time to be visiting, considering all the construction going on in USF. And I have to agree with the poster above, don't compare. I personally like Universal better, and I find it hard not to constantly compare when I'm at WDW, but I put it out of my mind and always have a great time.
Here's some tips from me:
Rides/Attractions you can't miss no matter what. No excuses: Spider-Man, Forbidden Journey, Pop Eye and Bluto's Bilge Rat Barges, Jurassic Park River Adventure, Cat in the Hat, Dragon Challenge, The Hulk, Mummy, Disaster, ET, Despicable Me, Simpsons, MIB, T2:3D
Rides that you should see, but understandable if you miss them: Poseidon's Fury, Doctor Doom's Fearfall, Dudley Do Right's Ripsaw Falls, Flight of the Hippogriff, High in the Sky Seuss Trolly Ride, Shrek 4-D, Hollywood Rip, Ride, Rockit
Hidden Gem: Universal Horror Make-Up Show. A really fun show, but only has a few showings each day, and has very limited seating. Make sure you figure out how it fits into your schedule. I wouldn't miss it.
More fun than it looks: One Fish, Two Fish, Red Fish, Blue Fish. Sure, it looks like a normal spinner, but ride it and listen to the song. It's hints for when to move up and down to keep yourself from getting wet. It's a blast.
Skip-able: Stormforce Acceleration, Caro-Seuss-al (unless you're a Seuss fan), Sinbad, KidZone shows
Warning about the IoA water rides: It's not "You May Get Wet" here. It's "You Will Get SOAKED". I've never been on rides that get you more wet. But they're all very fun, so I wouldn't advise skipping them. Personally, I like to wear a bathing suit to IoA, along with something to get changed into after riding them. Then once I'm done with the water rides for the day, I change and put the wet stuff into a plastic bag and a locker, and then pick it up at the end of the day.
One thing I'd definitely recommend is to take the time and explore. Especially in Islands of Adventure. The park doesn't seem all that big, but it has so many explorable nooks and crannies. Really comb over areas like Camp Jurassic, the JP land in general, If I Ran the Zoo in Seuss, and Me Ship the Olive in Toon Lagoon. There's so many hidden little details to enjoy. Also, if you're a Marvel fan, look for all the injokes and winks in MSHI.
I'm not sure where you're staying, but I enjoy exploring the Uni hotels, like the Disney resorts. Royal Pacific and Portafino are both beautiful places, and it's fun to travel to them using the Universal water taxis.
Let me know if you have any questions.