If one seeks pathbreaking cinema, this is not the film. However, if one is willing to refrain from seeking logic at every nook & corner, then this is a lovely joyride, albeit a tad long [the editing could have been tighter for sure]. The music is peppy, and a couple of songs, especially the title track & the one coming when the end credits roll are superbly choreographed. The cinematography is excellent, Canada's natural beauty sprucing up the visuals.
Now to the performances. Shahid is excellent, and the confidence gained from the experience of Jab We Met shows. Vidya Balan is well, as usual - an excellent performance, marred as usual by a terrible wardrobe [Manish Malhotra, where are you?], but her chemistry with Shahid is crackling. Om Puri is okay in a role which does not tax him one bit; and Juhi Chawla provides adequate support [though one wishes that she gets more meaty roles]. Himani Shivpuri is superb in a cameo. The support cast is quite good as well.
A small caveat: the film revolves a lot around lucky charms, talismans, and the "kismat konnection" - so you will need to make some allowance for that. That given, this is a clean, wholesome entertainer.
P.S.: Was it my illusion, or was Shahid actually trying to mimic SRK (in quite a few scenes)? Dunno, but I really hope I was mistaken...