I came across The Office on BBC America back in 2003 or so, having heard nothing about it. I was blown away with how original and different it was. I am probably more familiar with British culture than most Americans, and don't have a problem with accents, having grown up on Dr. Who, Monty Python &c. on PBS. But I think that's a very small part of it. What made the show so unusual was that the humor came from mundane situations with well-developed characters, and nothing seemed forced or written to be funny. Sometimes there were awkward silences, and sometimes nothing happened for a while. Just like a workplace documentary would be.
The US version is a good show, but not great like the British one. Partly because it was not original, and partly because it has gone on too long. It has lost almost all the documentary feel and is just a wacky workplace sitcom. With a show like The Office, two seasons and out was the better way to go.
Also, I've never thought Steve Carell came close to carrying the show the way Gervais did. Michael Scott is like an inflatable dummy compared to the characterization of David Brent.
--Justin