Altho Janicee has a point I always buy a flash pass you pay an exrta amount and you don't wait in line. think about it you wait on average 10-40 minutes to ride a 2-10 minute ride. yes there aren't that many rides but I doubt your only going to want to ride each ride only once. so lets do the math (using an average wait time of 15 minutes) you go to US for 5 hours without a flash pass you can ride max of 12-17 rides. with flash pass you can ride max of 30-150 rides. mind you this only takes into account wait time and ride time not time it takes to get in between each ride but you get the point you take out the wait time you increase the rides dramatically. the best bet is get to the park and see how busy it is if your not really waiting in line that long then don't worry about the flash pass. my general rule is if I wait more than 5 minutes from the time I reach the line until I sit on the ride then it is too long but some are willing to wait more some less.
How many days are you going in for? Because if you're going in for several days, I wouldn't buy it since there aren't all that many rides in Universal studios. If it's for one day I found that it was worth it, since there were so many people and many rides took over an hour of waiting. However, if you are going later on in the day, I wouldn't get it because when I went at night, I was able to go on many rides over and over again with no lines because there was really little people.