I got hold of an old Marshall lead 12 combo made in 1985 and fitted with a UK made Celestion. I wasn't too happy with the sound but didn't want to spend too much on this amp which kind of ruled out a Greenback. I decided to try this speaker based of the great sound that Blackstar and Marshall get out of them. I wasn't disappointed - the sound was not too different from the original speaker in the amp but the speaker is definitely more efficient making the amp louder for the same settings and the overall sound is just tighter, especially the bottom end which just feels a bit tighter and less muddy - still plenty of it though. It is probably no brighter than the original bit it is a 10" speaker so tends to be fairly bright anyway. All in all, I'm really impressed with the speaker, for the price it is superb. I know this is made in China but I don't care where it is made so long as the quality control is good and I have no complaints about this speaker whatsoever.
It is hard to give a good description of what a speaker sounds like, it has to be subjective and depends on many factors. I'm using it with an open-back 12watt solid state combo from the 80's at relatively low volumes at home. In my opinion it sounds a bit more 'modern' than a Greenback but not as much as a Vintage 30 does, it is somewhere between the two, probably closer to the Greenback but your opinion likely differs. Either way, it is a nice, solid feeling speaker with a good sound at a good price.