If you are avoiding this movie because you dislike the Duff sisters, fear not. Even though Haley Duff gets top billing, she doesn't get more than about 10 minutes of screen time, for much of which she's in the background, and maybe five lines of dialogue.
This movie is only slightly more improbable than a lot of seasonal romantic comedies. The trope of bringing an imposter as your date to a a family event is not really grounded in reality anyway, so if you're willing to suspend disbelief that far, it's a nice enough diversion for a couple of hours around Thanksgiving.
The cast is reasonably solid, if under-exercised, with some halfway decent comedy chops available (but not accessed) in Shelley Long and Sam McMurray. The two leads are cute and sad by turns, mostly at appropriate moments, and sing well together for one nice scene. Other supporting characters... well, they look their parts and speak their lines but don't expect to find gold in their emotional range.
The script and performances didn't quite gel, leaving plenty of avenues for both comedy and heart under-utilized. Real dramatic situations were barely nodded at in passing while the most potentially humorous moments were signalled more by the characters' laughter than by any similar urge in the audience.
If you combined 'The Family Stone' (where only Sarah Jessica Parker is lacking the necessary depth of character) with 'My Best Friend's Wedding' (where everything is deliberately shallow and the moments of heart stand out better for it), and made a college film class movie, this is about what you'd get.
