Rainbow Road

Rainbow Road and Bowser's Castle were the only tracks I was disappointed by in this game, so that should say a lot about the game. But even with the other tracks being amazing, I still wish they would've improved Rainbow Road more. You'd think they'd go absolutely insane with anti-gravity here, but they don't at all. In fact, it uses anti-gravity in much less creative ways than the other tracks. That and the music isn't even that good.

Although because Rainbow Road is one track that's in every single Mario Kart game, I guess it can be hard to come up with new ideas for it.

The music was a disappointment.
The track was not nearly as good as I expected.

I would have been fine with it if the director did not say that the track would be spectacular.

Yabuki wrote:One thing I do want to mention is Rainbow Road, that final course. We really want you to look forward to what we’ve done to it this time because it’s something else. It’s really spectacular.”

http://nintendoeverything.com/mario-kart-8-devs-talk-games-graphics-and-using-wii-us-power-balance-original-rainbow-road-is-really-spectacular-more/

When Yabuki said that I was thinking that the course would be based off of different plants from the Super Mario Galaxy games are something.

Yeah, I didn't have anything specific in mind, but I was thinking something amazing like they said. "It's really something else" is true, it's worse than any other track in the game. XD I was excited for this track originally.