I'm sorry if I come off as harsh, but dear god who made the jungle map!!
-Trees are a major pain in the ass.
-It's hard to get back into the air once you're stuck.
-It's hard to tell whether you're even going the right way if you're trying to get back into the air.
-Missing checkpoints is a major pain in the ass.
-The music, dear god!
That would be me, sir. And practically all of these have been addressed before.
Difficulty: I designed it to be fun for myself, I'm sorry for your poor flying skills. To rectify this, I am currently designing an easier plane track themed after early 20th century air races.
Getting back into the air: This is a problem with the checkpoints currently, they were not designed for planes (soon to be fixed).
Hard to tell which direction you're going: I kind of forgot about this one while building it, as it's hard to get lost in your own map. Will be rectified soon. Maybe.
Missing checkpoints: Do you mean the lack of checkpoints on the lowest parts of the map? Fly, don't drive.
The music: I think it's good, sorry. Nor am I to blame for it.
You know, with all the people having difficulty flying, maybe I should write up a brief tutorial on how to fly properly.