I skipped a lot of the American one because I thought it was going to be an exact copy, like what they did with the office, which is probably why you're asking the question.
I really like the British one, and if you have the time I'd recommend watching it, but if you watched the American one I'd reluctantly say, watch the first episode. If you don't get hooked then skip ahead to the last one.
They’re more or less the same but the ending of the British one answers the heroes questions and leaves the viewer with some questions, where as the fairytale ending of the American one answers all of the heroes questions and leaves the writers/producers of the show with a warm and fuzzy feeling.