Minecraft wiki entry for Best_biomes_for_homes, associated text: Extremely flooded. It is very hard to attempt to build anything large without reforming the landscape, though building a stilt house may be a solution.
Depending on equipment and skill level, the extra slimes may be overwhelming.
Witches can become a problem when near a swamp hut.
No villages generate here.
Bringing pets or mobs through the water on leads may lead to them being stuck under a lily pad and drown.
Water is discolored and not as appealing as water elsewhere.
Zombies may end up underwater and sink, turning into drowned. This makes nights in this biome noticeably more dangerous.