It's easy to go from the UK to US but it would be very hard to go back. The humour in the UK one is a little black and depressing (more of a train wreck, and it makes you uncomfortable) where as the US one, everyone one in the show is so quirky that the bad situations never seem as awkward or uncomfortable, just funny.
I prefer everything about the UK version except 2 things. I like the extended storyline of the US version, and the fact that Ricky Gervais is NOT in it. Usually I much prefer the UK version of something to the US take-off, but in this case, Steve Carrell is just so much better in that role. If you could put someone like Steve Carrell into Ricky Gervais' role in the UK version, you'd have the best of both worlds.
The American version is just not funny - poor take-off of the genuine article (UK version).
Ricky Gervais, love him or hate him, is a genius and The Office was the first of its kind in the comedy world.
The episode with the crazy dance was priceless.