Hello kristofk,
Unfortunately, I will be Rejecting your map.
The theme is somewhat original, floating island maps are very unoriginal and have been done many times, but there aren't any exactly like this.
The parkour is quite repetitive, as a lot of it is made up of normal blocks, fences & ladders. Try to experiment with a larger variety of blocks and items when building parkour, as well as the way you utilize these, as this will make your map overall more enjoyable.
Try to incorporate the parkour into the build a bit more, rather than having sections floating over the void. Sometimes, having an excessive number of jumps floating around the build and void can make your map look a bit messy.
The difficulty is good for a medium map, and the length is good for an expert.
Thanks for submitting your map! I hope to see more maps from you in the future.