First of all, this is not an offense to the great Mr. Bergman, but whether we like it or not, movies should be judged on their own, separate merits, instead of associating it with previous (or later) works, which ends up as a biased view.
The truth is that this is a very BAD film. For some reason I think even Bergman must think that.
It really seems as if Bergman and Nykvist just wanted to test how it was to make a film in color and Bergman just wrote the entire script in 2 hours or so. Even the short lenght seems to give support to this.
Really a film I'd recommend only for Bergman completists.