My main issue with Illuminations is the globe. It takes up a huge chunk of the show and it's difficult to see. The projections are very dated compared to the castle projections. I'd rather see more fireworks compared to the globe sitting out in the middle of the water.
Personally, I've also seen it so many times that I'm ready for something fresh. One nice thing about going out to Disneyland is that every time I go, there's fresh nighttime entertainment. Whereas I go to WDW, and it's still the same nighttime show, minus a few upgrades, as when I was 5. One of many reasons why Epcot is my least favorite park.