I just finished up watching the first and second season of The Office from the UK. It isn't as blatantly funny as the US version, but I think that is because I am not English. I laughed quite a bit, but I am certain I missed some things to.
My favorite part of the UK series was Tim (Jim's character). His looks to the camera were really good, and while Jim does it on the US version, I think Tim's were far better.
What I like about the US version better is that you get a far more character's interacting. In the UK version, you really only see David, Tim, Dawn, and Gareth (equivalent to Michael, Jim, Pam, and Dwight).
Gareth is a much more believable character than Dwight mostly because he isn't so extreme. Dwight is so far out there sometimes that you can hardly believe that he functions in normal society. Gareth is just a jerk.
I wouldn't say this is a must, but if you have access to it, watch it sometime and see what you think.