I watched the entire series within a couple of weeks, and the one thing that kept bothering me was the constant lack of continuity. While the general story lines and characters were interesting and engaging, many times characters would just drop off of the series, never to be seen, or heard of, or spoken of again. There were so many loose ends leftover by the end of the series that I had to wonder if the producers had any clue at all about what their jobs were. It seemed to me--especially in the later seasons--that the writers and producers just gave up, or just didn't care about the series anymore.
The final six episodes were very rushed--especially the last episode--and I cannot believe that so many characters--including the main character, Laura--didn't appear for even a moment in the last episode. Heck, there were main characters that didn't appear at all in the final season. I've noticed this trend with BBC programs, where actors and actresses seem to jump from job to job without satisfactorily completing their roll first, and no one seems to mind the mess it makes of the series' plot and story lines (Downton Abbey is a great example).
In conclusion, it was a fun way to waste some time on my days off, but I wouldn't really recommend it to anyone. It's sad, because most of the actors/actresses did a fantastic job throughout the series (those that actually stuck with it). But, in the end, I don't think that the producers or writers did the cast any justice at all.