I never understood why the critics hated them so much - they were grooving, very organic in their approach, the Motown influence was audible through all the white-boy-volume and I didn't think they were bad instrumentalists at all, not one of them. Farner was no Jeff Beck, true, most guitarists weren't/aren't, but he had grit, swagger and emotion. His voice (and Don Brewer's gruff vocals) I always liked. Mel Schacher, otoh, was a better bassist than in most bands playing high energy music around that time, but of course no critic ever listened closely to what he did.
Composition-wise, even a late piece of work such as Born To Die (recorded when the band atmoshere was less than happy) is a masterpiece.