The way I saw it, yes, it started out great in an "ends justify the means" kind of way. But along the way, it got to the point that he was just evil now, period. Yeah, dark side corrupts, etc etc. But it just made the arc way less interesting to me. I also didn't like how cheaply they dispatched him either. Basically had to have him fight while crippled and heavily distracted in order to kill him.
I don't remember Revan "losing himself" to the extent Caedus seemed to. Hell even Darth Bane's motivations remained more coherent and logical. But as I said, I understand why they did what they did with Caedus (to the arc's detriment in my opinion); to parallel Vader's fall.
As for your claim about 10:1 ratio of good to bad, well, it's subject to opinion I guess.
But how about darksaber, sun crusher, ysalamiri, all palpy's clones, crystal star (space werewolves? Luke joins some weird alien cult?), ewok adventures, holiday special... and on and on.
Don't get me wrong. There was plenty of great stuff. I wouldn't own 40+ EU novels if there wasn't, plus an assortment of comics. But a lot of it was batshit insane.
You forgot to mention Luke's
Body snatching computer waifu Callista