The idea of JOW works pretty well in current Epcot. Leaving aside its physical placement (it should have been an addition in the center not overtaking the entirety of a CC wing), I actually enjoy it. But, I think there is valid criticism in execution. It's trying to dance the balance between being a Moana attraction and an Epcot attraction. Some would say it dances the line well, enhancing it. Others would say it doesn't do each ok, but it succeeds on neither. Both are valid opinions to me.
I think a major issue is the new sections of World Nature feel very disjointed from World Nature itself (i.e. the Land and Seas). You have a very planted, very tropical entry now that leads to Journey of Water. Then the more corporate/modernist ascetic of Seas and The Land. I get 100% the idea that JoW fits into World Nature. But, from a design and landscaping standpoint, the idea doesn't translate to what you actually see in the park. If they redo the landscaping around The Seas and The Land to be more lush/tropical/dense in line with the new entry areas, that would change. But, JoW feels more separated from World Nature than it should.