they're pretty cool for darker, high gain tones with some retention of clarity, and without as much sag as the obvious (*cough* MESA *cough) alternatives. They certainly have a place in my ear, but I dont like them that much.
cr@p cleans, but thats not what its about. I've never owned one, but I dont think I've ever seen one gigged where the cleans were used. $% knows what goes on with cleans in studios with bands that use them.
I prefer stuff thats a bit more forward in the mids, mainly high mids, and tighter (they're pretty tight, but not that tight).
Great with a decent OD on top of it.