I know I'm a bit late to this, but I started this map last night.
Thusfar, I've got the starting island, rock island, ice island, crimson, corruption, spider, mushroom, beanstalk islands all done, Dungeon is almost half-done.
One suggestion, I'll make that I think would make this map a LOT better, is if you would have added a teleport hub in the center island. However, the teleporters won't work because there's one small piece of wire missing from each teleporter and you need to first find and release the Mechanic, buy a wrench, and a few wires to restore the teleporters on each island (the wire is cut on each biome island, not the starter island).
That way, it doesn't take such a ridiculous amount of time to get from one place to another even with the Flurry boots but yet you still have to explore on your own (but have a fast-travel method later).
UPDATE: Got almost to the end of the last island, ran out of wood and tried to use a shadow orb for light, wound up making a mistake and stepping on a switch, got knocked back into another switch and got killed, lol. I was like... a few hallways and 2 major rooms away from the last one. Well, I'll come back with more wood and finish it off. Was fun so far!
That last island isn't THAT bad, you just need to be careful and take it slow and bring lots of gel and wood and some rope. I think I blew almost 300 torches on the way down.
UPDATE 2: Apparently it is impossible. Summoned the Wall of Flesh, he turned out to be invisible. Wasp Gun would kill the Hungry, but the Wall Itself was invisible and the bees refused to hit it. Tried throwing magic daggers at it, still couldn't hit it. Probably because you filled the room with actuated blocks....