While WOC is incredible from a technical perspective, it has some serious flaws on the creative side that really stand out on repeated viewings.
One of the things that made DL's original Fantasmic! so great was the pacing, how the intensity builds and it keeps revealing new tricks throughout the show. One of WOC's biggest weaknesses is that it shows all its cards (except the fire and in-audience effects, both of which are used very minimally) by the end of the introduction with the main theme song, about 2 minutes into the 28-minute show. We see how tall the fountains go, we know the colors available, we know which heads move and which are stationary, we know which areas around the lagoon will interact with the show; there just aren't a lot of surprises to unfold after that sequence, which lets it drag in many places later on.
Where WOC is most successful, it reinvents imagery from film in a creative-yet-recognizable manner (the stampede) or in an entirely abstract form (Buzz/Zurg battle). But all too often, it resorts to simply playing familiar images on a water screen. While there's nothing wrong with that as an occasional technique, it's often used as a crutch to lean on, rather than letting the fountains take the starring role. Instead of including segments because they make for a compelling show, it often feels like they were included for the sake of having more familiar faces.
Some of the music choices are also dubious. While the show uses some inventive interpretations on under-utilized pieces to great effect (April Shower, Firebird), it also uses some that are serviceable in their original films but aren't terribly memorable tunes out of context (Wall-E score, Pines of Rome). And as the forebear of Steve Davison's big recent shows, it relies too heavily on those same few films and songs that seem to pop up in every single production these days. The World of Color song is also used too sparingly, only bookending the production, rather than being integrated into a more cohesive soundtrack.
There were also major revisions to the show shortly before opening (allegedly at Iger's personal request), and it shows. Many of the transitions are often choppy or non-sensical, or rely on characters quoting themselves out of context. The segments don't build in intensity from one to the next, but are treated as stand-alone elements. That multiple segments have been swapped in and out through the years, with no discernible difference in show quality (the Hellfire/Firebird to Pirates swap not withstanding), only reinforces the notion that the show's structure followed a modular plug-and-play model, rather than tracing an overall emotional arc structure.
Additionally, the quality of the show can vary widely depending which version you see. The original is pretty good; the various Winter Dreams iterations have fluctuated between good and mediocre; the 60th show was just plain bad. Although they're not as common these days, the promotional tags have ranged from excellent (Tron-core) to lackluster (Brave).
To me, World of Color is one of Disney's most frustrating shows. It is a big-budget production with impressive technology, but in a lot of ways it feels like a major missed opportunity. It's not bad, but it has so much potential that it just doesn't quite live up to.