m<.5*n
Scary because no keys can be lost. As the number of signatures required increases the risk also increases. Could be thought of as hard multi-factor authentication.
m=n
Could be used for small group funds that do not require much security. Least secure multi-sig option because it is not multi-factor. Any compromised individual would compromise the entire group. Group funds for a weekend or evening event might be a good usecase. A shared wallet might also be fun for some kind of games too. Besides being convienient to spend from the only benefit of this setup is that all but one of the backup/password pairs could be lost and all of the funs would be recoverable.
m=1 and n>1
n = number of signaures avaliable
m = singatures required to spend
Multi-Sig Usecases