Finished this last night, with the final season having arrived on UK Netflix a month or two ago.
Must have watched the first four seasons on a sort of one-a-year-ish basis, and then took a gap, because I've watched 5-8 in the last 12-15 months.
Enjoyed it overall - definitely a couple of times when it took a bit of a lull and strayed away from being a tense & involving series into something a bit more akin to an entertaining no-brainer, but solid enough and I'm glad I stuck with it. Plenty of memorable moments throughout, and I think they did a good job with the final season (even if that sort of coda-style ending can always seem a little jarring).
Glad they've drawn it to a close for now, and inclined to think that should be it for it as a series. Wouldn't have anything against it coming back as some sort of tight 'special' - a film of a three-part thing, for example.