I felt that the lack of fleshing out their attraction led to her seeming EXTREMELY unlikeable, and left me wondering what he saw in her at all other than her beauty. She was mean, unforgiving and immature, on top of the presenting problem of her major lie. What's to like? This coupled with his altogether likability led to an underlying unbelievability of their entire relationship. Yes, the movie was about the two dads, but the marriage/wedding needed to be a stronger point from which the movie was scaffolded.
All other aspects of the movie, most of which were already commented on, I found fun and entertaining. I laughed out loud numerous times, especially by chef dad. I loved how he bonded so easily with Stephen. They were much more adorable together than the romantic couple was.
Jamie's performance was as I would have expected. "The shirtless scenes were gifts, there is no other explanation for it!" YES! This is what the pause and rewind buttons were made for.