I watched this when it aired on sky living, but in standard definition.
Although I enjoyed it very much, the picture quality did not do it any justice. What a revelation upon seeing the blu ray!
It is the only way to appreciate the series and to me was like watching it for the first time.
In any event the series withstands repeated viewing, with a strong storyline and reasonable acting throughout by the (mostly) young cast and seasoned veterans like Xander Berkely (inspired choice) and Maggie Q (kick-ass beautiful).
I am also a massive fan of Luc Besson's movie but this is completely different, only basic elements of that film are retained here.
Obviously you need to like 'invincible assassin' type movies to enjoy it
really, probably not for fans of the English Patient...