I had only ever used Express for Orlando's parks (since we're SoCal natives). However, when we finally returned to USH in April, we didn't want to wait in a 2 hour line for Jurassic World or Mummy after being away for so long and forked over the 100 bucks each for unlimited Express. It was awesome and totally worth it. Yes, it skipped the entire lines and allowed us to do so over and over again. Went on Mummy three times, Jurassic World three times, Transformers twice, Pets twice, Potter twice, Potter coaster once and it allowed us to skip the tram tour line and sit in the front car. We could have done it much, much more but we wanted to take our time and enjoy the park.
They have a cheaper add-on option for like 60 bucks where it's once per ride and not unlimited. Normally, we never bought Express because lines there were always at least manageable and we went all the time. But with everyone finally coming out for a visit to the parks after being locked away so long, I'm thinking we may visit just a little less but buy the Express pass when we do, to make the trips we do have more carefree.