I like her, I don't think she has headliner power. I was not that impressed with bridesmaids, but really loved her in Knocked up. Her part in Extract was pretty small but perfect for her. SNL is pretty much unwatchable and has been for the past 20 years.
I think she is really funny. That being said, I didnt really get Bridesmaids. I though that movie was kinda miserable, with a really funny shit scene stuck in the middle.
Everybody says "SNL was better when..." I would catch it every now and then and still get a few big laughs each show (but not like during "MY" cast). Wiig was probably the best one on the cast at the moment other than Seth Myers, but he only does Weekend Update and not many sketches. Bill Hader is pretty funny also. I'm sure she'll go the way of Maya Rudolph and do a few more movies before ending up on a sit-com. I just hope none of those movies are based on her characters... while funny they were too gimmicky to be feature film leads.