I did enjoy it overall. One inherent problem with the film, however, is that it's pacing is pretty bad. It lasted only about 1h45 but felt like it was an hour longer. This is mainly because about 2/3rds of the way into the film, rather than resolve the film or at least end it on a strong note, Wellingston insists on pushing it further and further into the realm of ridiculousness.
Sarah Polley is the stand-out here. The cast, overall, works quite well, and Shane's roommates are especially amusing, but Polley is the one to watch. There is a scene in her flat with Polley and Kirby on the couch, he's staring at her, and she goes through a barrage of facial expressions, body language, and nearly no dialogue. She is able to say so much while barely saying anything. This is the kind of brilliant acting I expect from Polley - someone who is a strong character actress, who can assume roles right down to the little quirks and twitches. The way her eyes look, her expressions - you can see the difference in her character type when watching Go vs Guinevere vs Sweet Hereafter vs Luck. Each character has their own distinct personality. This is VERY difficult to portray in film, to be able to be a completely different person each time you step in front of the camera.
Overall, Luck is a decent film. I'm happy I saw it but I wouldn't go out of my way to see it again. I'd give it a 6.5 out of 10, with a 9/10 for Sarah Polley.