We just came back from there, and it was our first time. While Mrs. Mohandas did 5 days of training at Kennedy Space Center, I was with the kids for 12 hours a day for 3 days at these twin parks. I really had no idea what to expect, so I'm leaving this here for other people who might go:
Two parks - Islands of Adventure and Universal Studios. They are so close to each other that it makes sense to get a Park-to-Park pass. And the connector for them is the Hogwarts Express, which in and of itself is a park ride.
Main difference between the two parks - Islands of Adventure has more outdoor rides, and a couple indoor ones. Universal Studios has more indoor stuff/attractions. This means that "Islands" is more vulnerable to bad weather, which really body slammed us on our first day when we had torrential downpours.
4D Rides - One thing that going to Disney and Busch Gardens parks did not prepare me for were the "4D rides" that Universal has and that the others do not. I don't think words can do justice to how immersive and fun these rides are. You are jolted and spun around in various scenes that make you feel like you are flying or falling, or being attacked, etc. The rides that have this feature are "Spiderman", "Kong's Reign", "Harry Potters Forbidden Journey", "Escape from Gringotts", "ET", "Simpson's Ride", "Mummy's Revenge", and "Transformers". The first three are at "Islands", and the second five are at "Studios". All of them are great - especially Spiderman and Forbidden Journey, which seemed to be longer rides and have shorter lines when we were there.
Potter Stuff - If you are a Harry Potter fan, you will probably be pretty blown away by the parks. Each park has a Harry Potter sub-park - in the case of "Islands", it's Hogsmeade. And in "Studios", it's Diagon Alley. We had heard that the first year or so, these two parks were completely overrun with visitors and hard to get into. When we were there this week, they were crowded but you could do basically anything you wanted to do or visit, except maybe for seeing the "wand choosing ceremony" at Olivander's, which I think is at Hogsmeade.
British people - this was another cool surprise. There were a lot more British people at Universal than any of the other parks we have visited, like Disney. And it especially seemed to be the case when we were in the Potter areas. At one point, we were on the Hogwarts Express, sitting across from a family of four, and the conductor came by our compartment and said, "welcome - next stop, London!", and this British kid sitting across from us turns to her dad and says sarcastically , "I guess we're going home early..." My son and I looked at each other and tried not to laugh.
Parking - if you are not staying at an on-site hotel, you will end up spending about $20 a day to park in a giant parking lot next to the parks. However, this lot is MUCH closer to the park entrance than Disney Magic Kingdom or Animal Kingdom. And you are out of the sun the whole time you are walking to the entrance. It is VERY orderly getting in and out of the parkign lot, too. No problems whatsoever.
Security - it's more intrusive than Disney, which just inspects your bag. Here, it is exactly like the airport - you have to take everything off of you, belt, phone, coins, keys, purse/bag, and put it on a conveyor belt to be scanned.
Roller coasters - their coasters are really good (Hulk, Dragon Challenge, and Hollywood Rip Ride Rockit), but they have the most insane security I've ever seen in a park. You have to put EVERYTHING in a complimentary electronic locker that is right next to the ride. Then, you walk through a scanner like they have in the airport. And even your credit cards are going to set off the scanner, at which point they will wand you - seriously. I got sent out of line twice, and had to leave my kids behind temporarily while I got sent back to the lockers to put stuff in there like my car keys, and some other thing that I can't even remember. But they let you back in a special path to rejoin your group, so it's a hassle, but not a huge one.
Complimentary lockers - they are free for up to 90 minutes. And very advanced. However, they have done some screwy stuff by making them work differently at some of the rides. For example, most ride lockers use fingerprint scanners to let you access your locker. But the Hulk coaster requires you to use your park pass barcode to get back in. I got locked out and need security assistance because I was in a hurry and put all my stuff in there except my wallet. And finally, there is another locker (I forget which) which makes you create your own six-digit passcode to get back in your locker. They should just standardize on the fingerprint. Also, whatever you do, DO NOT over stuff your locker and accidentally jam something like a strap in the door, because I saw numerous times that even a locker attendant could not get the locker open without having to spend precious time hunting down a special tool that would open the jammed locker.
The worst attractions - "Eighth Voyage of Sinbad" is billed as a live-stunt show. Relentlessly corny jokes and an incoherent story line. I literally fell asleep sitting up three times during it. I asked my kids what they thought, and they said it was okay, so I held my tongue - but it is awful. Only go there as a last resort. "Poseidon's Fury" LOOKS like it's going to be a great attraction. But it was the biggest tease - laboriously going from chamber to chamber while an Ellen deGeneres impersonator pretends to be a hapless assistant to a big-time archaeologist. Never again. These are the main attractions in the "Lost World" section of the park, which really should get lost. You know things are bad when the talking fountain is the best part of the area.
Another disappointing attraction - "Jurassic River Adventure" - looks very impressive from the outside and has a Splash-Mountain type finale, but trust me, nothing is happening on the rest of the ride.
Stuff we didn't do - "Doom Tower" - which basically drops you from a ridiculous height - looks pretty cool but my daughter didn't want to do it. Also, did not do the "Bilge Rat Rapids" or "Rip Saw Falls" because we had no desire to spend the next 2 hours walking around soaking wet.
Wait times - Like Bush Gardens Tampa, the park has updated displays telling you various wait times for rides. They turned out to be pretty accurate (the signs and the wait times), so we were never stuck in a line for more than about 50 minutes and that was rare. One ride was really good and had a very short wait time because it is kind of isolated - Universal Studios' Mummy's Revenge. This is an indoor coaster with a lot of special effects. It had 10-15 minute waits when we were there - we got on it at will basically. There is also an app for wait times that you can download to your phone, but I couldn't do it because I forgot my iTunes log in.
Food - about as expensive as Disney. The cheapest place to eat seemed to be Krusty Burgers - which is an eatery in Studios. Lots of different stuff to eat and plenty of tables to sit at, which is very different from the rest of the parks. Also, was VERY surprised at the one-off restaurant in Diagon Alley - Leaky Cauldron. They serve traditional British food, and I finally got to try Toad in the Hole! My kids liked it, too, but had fish and chips for themselves.
Butter Beer - this is going to single-handedly bring back the popularity of cream soda. People were waiting in LONG lines for it, and my kids loved it.
Express Pass - forgot to mention this. Kind of like with Disney and Busch Gardens, there is an Express Pass that gets you into a special shorter line. However, you have to pay for it. And it's complicated because there are two versions - a one-time only per ride pass and an unlimited one. It would have cost me an extra $240 for all three of us to add this feature to our tickets, and for our purposes, it was not worth it. We managed to get on all the rides we wanted to, and some multiple times, while we were there. But it is clearly very popular and very effective because people who had them were whizzing right by long lines on some rides.