It can't just fall off.

You have more freedom to move around as you don't have to worry about it falling off.

As long as it was Peverell's one, and not one of those cheap ones that wore off after a while.

I would disillusion my self and where and invisiblity cloak, but the invisibility cloak is good for if you can't perform the spell

Probably easier, you think?

It's soooo magic =)

If you need to be seen quick it'll be easier than doing another spell(example someone hears you noises or footsteps and thinks you a danger to them or others.)

heehee XD

the disillusionment charm could wear in that waterfall thing in gringotts unlike the invisibility cloak

It would be so fun to run around in an invisibility cloak!

So you can others if need be.

The Disillusionment Charm makes you feel cold, I don't like that