To say the Cobra is not worth owning because of "quality" issues is blasphemy. They are a pretty sound amp really, I've been around numerous Cobras and none of them have had any serious issues. It seems most of the people here have said they didn't have any issues.
The thing with the Cobra, is that it has such a unique voicing that is raw and brutal. For those guys that just own one or two heads and want to keep it that way, then yeah maybe it's not the amp to own. It does clean well, and metal even better. Not much in between. It's the most brutal amp I own, and I also own an Uber rev 2, Herbert, Ultra Lead, etc all in the same room. For those that want a big arsenal with unique items in said collection, a Cobra is a great amp to acquire, and at what they are going for these days it's an easy amp to afford.