Also "isn't as funny as it used to be". Used by long-time readers or viewers of a humorous
magazine,
comic book, or
television show (extend this to any other
medium you want) to describe the current state of that magazine/comic/show. Usually,
IMO, the quality of the thing in question hasn't decreased -- rather, the person doing the
criticism has just become used to that type of humour, so it no longer inspires the
jaw-dropping hilarity it did when it was new.
Has been applied to Viz, Knights of the Dinner Table, and Mad Magazine to name just three.