We're led to think that Grandpa will end up reversing roles and educating Grandson about how to stop playing games and communicate honestly, respect women, and create meaningful relationships -- something Grandson has been unable to do in his own life. But (spoiler alert:) the opposite happens. We learn that the object of Grandson's affections (Marla Sokoloff) has been manipulating him more than he's been manipulating her, and has taught her grandmother (Roberts) to do the same. There, I've ruined the ending for you and you don't have to go see it.
The characters all deserve each other.
"It's a miracle!" exclaims our re-energized and rising hero. It wouldn't have been a miracle if he had been on heart medicine -- it would have been a death scene. How funny is that? You can view this scene online and decide for yourself.
If you must see this (and I don't recommend it, unless you want to see if you agree with me), please take a teenager with you and plan a long talk afterwards to debunk everything you saw. Otherwise, your teen might see it on his/her own and believe the dating advice aimed at both young folks and seniors.
My verdict: Ick, skip it.