As seen HERE:
Katsuyu instantly or at least very quickly (no prior warning) provides Shizune and co. with a shockwave-dampening cushion. Explosions not actually close enough to BURN Tsunade wouldn't have much effect, if any at all.
Katsuyu has a liquid-type body. It's gelatinous, and as such, would make Tsunade able to completely ignore sound-based genjutsu, like Kabuto's liquefaction technique does.
Do you agree?
EDIT: Slugs are useful. They look like they would be fun to bounce around in.