Just returned from Universal Studios.
It was fun, but definitely not as good as IoA. Some of the attractions are really, really dated (Twister is downright embarrassing), but there's still plenty of fun to be had. Mummy was pretty cool, and the Rockin coaster (or whatever it's called) was surprisingly good. Lots of airtime, which is always fun.
I will give credit to Universal's employees - they are uniformly excellent. They're not as seamlessly integrated as WDW's employees, but I was amazed at how efficiently they loaded and unloaded riders.
While it falls far short of Disney at variety and theming, and far below a place like Cedar Point in the variety and intensity of thrill rides, it's still a very nice pair of parks. However, I don't know if I buy it as a vacation destination in the same way as WDW. I got through both in one day, and I'm confident a large family could get through them in no more than two.