Minecraft wiki entry for Best_biomes_for_homes, associated text: Limited space for building on the ground due to the thick tree foliage.
Falling out of a tree is easy and can be fatal.
The thick vegetation makes it very difficult to navigate.
Hostile mobs, especially creepers, can be camouflaged in the green scenery.
Can generate more lag than other biomes.
Cannot obtain pufferfish or tropical fish when fishing.‌[Bedrock Edition only]