I liked it - used it for work at a daily newspaper. But we upgraded to the Mark III and sorry to say, it's far superior. Not just technically but the files are cleaner and a have a wonderful -- I know this isn't a technical term, but a much nicer presence to them.
I found the higher ISO shots on the original 5D to not have a 'filmy' look at all to them but just plain noisy.
Credit where it's due, the shot posted by the OP is a beautiful one and if that's the type of image they get from it, then they are clearly correct and more power to them.
But for my experience as far as DSLRs go, progress has been clear and unmistakeable.