My overall view on Mumblecore in a few words
"Mumblecore movies overall are a lot better in memory than they are to rewatch."
I've seen several of them and I appreciate the organic way the films are made by groups friends for the pure hell of it, but for the most part the films are boring and don't stand up to repeat viewings.
My two favorite Mumblecore films:
MUTURAL APPRECIATION.
THE PUFFY CHAIR.
Although The latter film is probably not really Mumblecore as it has a plot and a hell of a lot more visual scope cinematically.