We all have one of 'those' quilts in our quilt making history.
Put it aside - out of sight - for about 6 months. 6 months is usually time enough to let your bad memories of making the quilt get foggy enough to evaluate the quilt more objectively. If you are still disappointed with it after 6 months, then finish it up and donate it.
We all know the saying "Beauty is in the eye of the beholder" I suspect this quilt just needs to find the right 'beholder' to love it!