Seems like a number of people commenting about the UK version (negatively mostly) don't know that it started with a pilot that was much different than the rest of the series. A bigger difference than comparing the US to UK version in fact.
The first two episodes of the US version combined are a remake, with a number of changes, of the UK pilot. However, incorporating a lot of the character traits/backgrounds of the rest of the UK series. Anyone having started to watch the UK series with episode 1 missed a very important introduction to the characters. Find the UK pilot and watch it if you haven't. It will add a lot of background for the rest of the UK series as well as provide a better basis for comparison to the US version thus far.
Both series are good. The US version has been a pleasant surprise, I didn't think it would be half as good as the UK version.
I'm more vested in the UK version at the moment, which just started its third season. It will be interesting to see where the US version goes and to find out how many episodes they plan to film per year/season. In the UK it's only 6, which feels rather short.
