This comedy is essentially a goofy premise with some nutty dialog and set pieces pasted onto it. But it's watchably entertaining, even though the filmmakers miss almost every opportunity for sublime absurdity.
It's Johnson's committed central performance -- in a movie with a lot of shortcomings -- that only underlines the fact that he's got an awful lot of charisma and screen presence and hasn't yet had a truly great vehicle to channel that talent into.
The one element that lifts this above utter tedium is the presence of Stephen Merchant as tooth-fairy administrator Tracy. That he manages to come away with his dignity intact is testament to his skill as a comedian.