Now, I saw this movie with five girls who thought it was great, so your mileage may vary....but I thought it was just so-so. The big problem I had was with the two main characters, both of which I didn't think were likeable. I mean, I wasn't rooting for them at the end because they had both turned me off so much.
As for Robin Williams, I like him, but he didn't have much to do in this movie. He played the minister, who was really pretty creepy (bugging their apartment, having a mini-me of about 12 years old). If you missed it in theaters, I wouldn't even bother giving it a whirl on DVD.
This is such a fantastic show and the perfect counter to MacFarlane overload. With the family dynamic played up the way it is, I'm pretty sure this is going to end up the successor to The Simpsons. It can slide right in to that 8pm Sunday time slot.