The theme isn't very good, as biome maps are very common. They can still be accepted, but the build and parkour would have to be absolutely outstanding for that to be the case.
The build isn't necessarily unattractive, but a similar shape is used for all the islands, giving it little variety and making it a bit boring. You could also try adding some detail relevant to the biomes.
The parkour is very repetitive, although I would consider it fun. Also, it seems a bit long for a medium, so I'd suggest going with hard as the difficulty; that being said, I'd say the majority of jumps in the map suit easy/medium moreso than hard.
I also found 3 skips (and an impossible jump):
You can't jump into the hole in the side (which is where I assume you're supposed to go) but you can skip the entire islands parkour by jumping to the left ledge with speed.
You can jump straight from the tower to the left ledge of the island, skipping all the interior parkour once again.
And for the last skip, just jump on top of the island instead of the white glass panes and you skip all the end parkour.
Overall, I think that you have a lot of potential as a map builder, but this map just won't do it, so I'll have to give it a -1. For your next map, try a more original theme and some more varied parkour, because I can tell you aren't a horrible builder. Good luck!
Keep in mind, I am not an official map judge; take my review as that of a normal member of the community <3