I was excited to see this because John C. Reilly is awesome and the musician biopic was ripe for mockery. It also marks the first movie I've seen on Blu-ray, which didn't make much of a difference to my eye.
After finishing it, I realized that I want my comedies to surprise me. Not in a big plot twist, not in some brilliant joke, just something odd and funny enough that I didn't see it coming. Besides the songs, which were enjoyable and often funny, most of the jokes were obvious and, like a bad SNL sketch, repeated throughout the movie. I know they were meant to be bad in order to parody Ray and Walk the Line, but without the element of surprise, they were flat. How many times can the hero rip a sink out of the wall in a fit of rage and self-loathing?
The intro sequence in which 6-year-old Dewey experiences his Traumatic Life-Changing Event (he slices his unbelievably brilliant brother in half with a machete) was almost painfully bad. I did enjoy the striking age difference in his high school scenes, but instead of letting it be, he has an argument with his 13-year-old bride (who looks 30) about how young they are. I got it already.
If the cast and crew involved hadn't been as famous or as talented as they are, they might as well have named it Music Legend Movie and sold it as the next movie brought to you by "the guys who made Scary Movie." It had at least as many obvious double entendres and it never let you forget that you are watching a parody movie. Flawed as it is, Christopher Guest's A Mighty Wind covered similar ground in a way I found a little less off-putting.
I did laugh while watching this movie, and the songs were definitely listenable. The ending wasn't horrible (and Dan Bern's song over the credits is cute). You might enjoy it. But you might roll your eyes a few times, too.