Last night in the pub we realised that there has never been a good Robin Williams film. People professed to soft spots for The Fisher King, Aladdin and even Hook* but the general consensus was that Williams is the worst thing in these movies, and his performance pulls them into bad.
As Mike pointed out, any actor whose signature scene is putting out a fire on his fake breasts is not one whose career is in anyway salvageable.
*Hook, whilst a terrible idea, belongs to a favourite genre of mine: what happened next movies which imagine sequels to famous literature. As a genre it is nearly always appalling, except where horror movies are involved (Bride Of Frankenstein is a stone cold classic, but then this Frankenstein bears little relation to the book anyway.)