It takes a really strong performer to maintain an audience's interest for two hours. I personally liked the one-person-show by actress and comedian Julia Sweeney called "God Said HA!". She told her true life story about battling cancer while trying to break into and stay in show business. She also talked about her mostly dysfunctional family and her views on religion as a practicing atheist.
Sometimes I think a one-person-show can get a little tedious if the pacing is not good, but when it's done right by professionals, I'll forget I've been looking at the same face onstage for an hour or two.