A great first showing!
All the maps have pleasant music and nice visuals. CNK Out of Time is a solid port that I really have no issues with, it's adapted to 'Kart very well.
As for the other two maps, I feel that the road in both Arid Temple and Indigo Circuit is a bit too wide. You put certain obstacles or points of interest on the outside that feel punishingly obsolete due to the sheer distance you have to travel to get to them. The wall springs, as well, feel kind of like a moot point. They are punishing to players who would already be punished, and don't really add anything where they are placed right now.
Overall, though, I think the maps look great and are really pleasant to play. I think Indigo Circuit is my personal favorite, each section feels relatively distinct from the other and the music bops!