I just recently watched this version of The Office (UK).
I did watch the US version first, back when it was airing and I loved it very much at the time.
For a long time I was curious to watch the UK version because of it being the original, but mostly because I've read so much praise when comparing both versions. The majority of critics I've read always put the UK version way above the US version.
I discovered that I'm not part of that "majority".

There is the bias of having watched the US version first, plus the obvious personal taste, and by the way, I'm not a native English speaker. In almost every way, I prefer Michael to David, I prefer Dwight to Gareth, I prefer Jim to Tim.
As manager, Michael Scott had much more depth in every aspect. Dwight Schrute also was much more fun and authentic in the shoes of the Assistant (to the) Regional Manager. The UK version is also too short. The romance between Tim and Dawn, which is a big part of the show, is very unsatisfying in this short arc. We barely see the inside of the warehouse. There are characters that disappear completely for no reason at all and you never find out what happened to them (ex: Donna, Ricky).

In almost every way, I prefer the US version. The length of the series is part of it, but I think that the UK version focused too much on David Brent, which made it way more dull, and didn't give enough room for diversity from the other characters.