I also think Celestial Park seems kind weak—that's partially because Epic Universe's story device is kind of weak too. I think the story is roughly "you can explore a universe filled with exciting worlds using the portals of the gods and they're Greek gods just because!" Epic Universe's structure reminds me of the Magician's Nephew, choose your portal and go to a different world! One of the big problems with this concept is that there's no explanation as to why certain worlds are present while others are excluded. Why are the Greek gods sending you to see Donkey Kong? Maybe that's one of the labors of Hercules I missed! There's really no obvious organizing principle behind the park's constitution.
Celestial Park was by far the weakest element when I visited a few weeks back. Overall, the park is great, but the hub felt incredibly generic and lacks an appealing weenie (that ugly hotel does not count). Perhaps it's better at night, but it absolutely did not convey anything 'celestial' to me during the day. It reminded me most of Epcot, but worse since almost everything is silo'd off creating a lack of cohesion. Plus it's kind of ugly (which I'm sure will improve when the tree grow in). The fountain is nice (despite the ugly hotel looming behind it) and I loved the coaster, but it just has very little charm otherwise.
As for the greek gods sending us to DK: at least that's a different universe or planet or whatever. It amuses me that half the lands "celestial" park leads us too are Earth/European based, with HP and Dark Universe
I'm so very annoyed the AR tech wasn't saved for a Luigi's Mansion attraction, which would make so much more sense. Not only could the AR glasses fit in-universe as allowing for ghost-vision or whatever, but the inherent transparency of the AR effects makes total sense for the ghosts tooMario Kart is a better ride without the AR goggles -- it's still a strange fit for Mario Kart, but the sets etc. are good. The AR aspects are just distracting and make the experience worse.