The first few movies were really quite good, and though you knew it was fiction, it incorporated enough real-life stuff and was filmed in a style that created an illusion of it being a documentary rather than a scripted movie.
The illusion has weakened with each instalment (I'd say from 1-4 are good, 5 is mediocre at best, and each one after that gets worse and worse), with number 7 getting to the point of being barely watchable - badly keyed green screens, "in the moment" reaction shots that were very obviously set up from the camera position (and the poor chroma keying), and "effects" that are far from special, e.g. He fires a pistol where the muzzle flash is very obviously added on in post, there's no recoil, the action doesn't cycle, and no cartridge is ejected. It's just starting to feel lazy at this point. It feels like something cooked up by a group of amateurs in an internet forum.
Despite this, I'd say these movies are all worth watching the first 4, and if you want to understand why you needn't bother after that point, watch the 5th instalment. The 7th was really bad, the 8th is somehow worse. Any doubt that this was a movie as opposed to a documentary is completely destroyed. If you've watched the other 7, you may feel as though you may as well watch this one, I'd recommend using your time more productively, perhaps by putting wooden toothpicks under your toenails and kicking a wall as hard as you can.
At this point I feel like I've started watching a TV show, and it's a few seasons in, and it's got really terrible, but I keep watching anyway because I've sunk so much into watching up to this point. It's really a shame, because I found the first few movies to be captivating and enjoyable. Now it just feels like content on YouTube generated by a user with no experience in script writing, directing, or maintaining a cohesive and compelling plot.
I think I've reached a breaking point, and I won't be watching Blackwell Ghost 9 if and when it comes out. Sometimes, you just have to cut bait and admit to yourself that you're wasting time on something that's no longer entertaining or enjoyable in any way.