A solid 7.5 out 10. It's misleading gauging a show that spans 8 seasons on just one single IMBD rating. If I'm gonna invest time in a series that I didn't catch 10 years ago then I usually look for one that rates pretty high, usually more than 8. But it makes sense to view the ratings from individual seasons, maybe even each episode.
I watched seasons 1 thru 5 and thoroughly enjoyed them all.
Then season 6 just seemed to drag. The Doomsday Killer story arc was so boring. Biblical, formulaic nonsense that I gave up on and stopped watching after episode 3.
A year later and I gave it another go and, to be honest, the rest of season 6 didn't improve at all but then, the very last minute of episode 12 ended with a season cliff-hanger that was just too good not to watch season 7.
And I am so glad I did....
Season 7, best season ever.
The final season of the series, season 8 was back to tedious in parts, but wrapped up with a satisfying finale.
Overall a solid 7.5 from me.
Except for season 6 (5 out of 10)
and season 7 (9 out of 10)
But wait, there's more...
I have just found out that after ending in 2013 there is now a 9th season just finished shooting.
May well be released before the end of 2021..... I can't wait.