Reading many reviews about this movie including some of the comments in the forum, I have came to a conclusion that many have either not really seen the movie, or made preconceived idea that the movie is bad because Katherine Heigl is in it. Add that that is a LGBT movie, than the movie really must be that horrible.
But, I have seen the movie and I liked it.
If you watch the movie with open mind, then you would actually see that the theme of the movie is quite great. It's a story about a family who had no idea that daughter/sister was a lesbian. That she is getting married to her "room-mate", who turns out wasn't really room-mate but her girlfriend of 5 years. It's a story of family coming to terms and dealing with facts, that they had been lied to for a long long time. It's very hard coming out to your family, because you never know how they will react, or say, or think of you. And this is why it has taken Jenny so long to come out to her family. Her fathers reaction is a very big reason why many stay in closet. A lot of reviewers say that Bledel and Heigl do not have chemistry. Considering that they shared very little screen time together, there really wasn't much time for it. And the movie really was not about their relationship.
It's not the movie of the years. It's not a movie that will earn countless awards. But give the movie a try, give Heigl a try because she was good in this role.