Sandler's style of comedy is brash, physical, slapstick. Stewart's is subtle, cerebral, dry. He's at his best playfully tossing his neuroses into the air, not wearing a bland tie. He brought a intelligent sweetness to the role of foil for Gillian Anderson in Playing by Heart, but here he's a vehicle for delivering lines. Reluctantly, as required by the stereotype he's managing to evoke.
Some parents relive their childhoods vicariously through their kids.
Sandler doesn't need to do that, since he has never stopped living his childhood in the first place. Along the way, he meets another woman, played by Joey Lauren Adams, who had a great role as Ben Affleck's semi-girlfriend in Chasing Amy and has done almost nothing since. The script certainly doesn't give her much to work with, and she doesn't do much with it. Maybe next time. In the end, it's well-intentioned, a nice morality tale.