I actually liked the tone, premise, and flow of the movie. And it was interesting to see the female lead be platonic best friends with one of the grooms, without giving his fiance any cause for worry. But the movie was ruined by four mistakes:

The first bride wore something hideous on her head.

The second couple chose their careers over each other. That's a tragedy! If you're gonna have them cancel their wedding, make it because they realized they're not right for each other. Basically, make us want them to come to that conclusion. Wedding Bells handled that better.

It would have been great to see more of the third couple's reconciliation.

And the late-movie conflict felt forced. Why can't he just take one last trip, finally fulfill his dream of photographing the Southern Lights, and THEN settle down with her? For that matter, as a magazine writer who emails her articles, why can't she just go with him to Australia?