I disagree completely with that Guardian review. Just because it's not all jump-cuts and split screens doesn't make it slow. I'd say it's normally paced and the story moves along at a natural pace. The plots are not dense or confusing although it helps if you saw series 1. This weeks episode was particularly good and is setting up some interesting potential plot directions, I think.
Where I think it is sometimes a bit too self concious is in the smoking and drinking. Because it is so shocking to modern (especially US) eyes it seems they try to overdo it and get it into every shot. I grew up in the late 60's and 70's and know it was more common then (hell one of our teachers used to smoke on playground duty, mind you he needed it at our school) but it's a bit OTT.
Well if the Guardian scribe doesn't like it tough, there are plenty of us who do (and on the ratings the show is shown several times on BBC4 and BBC2 so I expect the cumulative figures will be much better than the Guardian's quotes)