Early Nickelback was pretty damn good. It had an appealing roughness to it that worked well with their sound. But by the time All the Right Reasons came out, they'd gotten too polished and, I think, too focused on making sure they had some smash hit singles up their sleeves. I think they started to focus too much on commercialism and too little on staying true to the sound that made them good. This resulted in things like production that made them sound sleek instead of raw and tracklists that contained "If Everyone Cared" and "Side of a Bullet" back-to-back.
When Dark Horse came out, I gave it a listen or two, dismissed it as utter trash, and decided I'd lost faith in the band entirely. But the first few albums...good stuff. Shame they'll probably never recapture that.