Made sense to me.
The Knights of Cybertron left Quintessa because she deceived them. For what reasons, we don't know precisely, but they don't take to being lied to. They arrived on Earth sometime before the middle ages but probably after the Fallen and the Original Primes were there. Quintessa/Quintus Prime has been forgotten by Cybertronian history and and the Fallen and his brothers were referred to as the "original" Primes probably because Cybertronians didn't realize that Quintessa, Vector Prime, Solus Prime, or any of the others existed. It was always in doubt who they were created by, and Cybertronians thought of their origin though the All Spark, which was created Quintus Prime (however, not stated in the film).
It would stand to reason that the Quintissons (still assuming that's who was seeding Earth in AoE) were created by Quintessa. They're literally Quintis-sons. They might have been created to collect metals to bring back to Cybertron for Quintessa to use to create the Cybertronians. Quintessa might have hired Lockdown under the guise of the Quintessons as a race to bring here the Knights of Cybertron back to Cybertron, but Lockdown, being a 'modern' Cybertronian thought she meant the Knights Teminous, which Prime and Grimlock were a part of. Also unrelated to the Knights of Cybertron that were Quintessa's body guards, but how would he know that?
After AoE, Prime shoots into space looking for his 'Creators', but ends up finding Quintessa. Lockdown didn't exactly do what she wanted him to do, but she can brainwash Prime to retrieve the staff of Merlin, kill the Knights of Cybertron, and destroy Unicron.
Not exactly all explained in the film, but seems perfectly logical to me.
I can't agree with this. There were lots of stunning shots in TLK.
I'll somewhat agree with this. As I've said above, it felt like two different movies smushed into one, and the pacing showed this.
This is very subjective. While I've never cared for the foul language used in the films (it's a live-action Saturday morning cartoon, why are there cuss words in a film that's supposed to be targeted to kids?), the writing seemed to be an upgrade from 2, 3, and 4. Anthony Hopkins' character especially seemed to be very nuanced, and the performance reflected this.
Cogman was also a really fun character.
I realize some people just can't stomach these films for whatever reason, maybe because of the fast pace that they seem to have. They throw a lot at people in a short amount of time, and it's hard to catch everything sometimes. I'm certainly looking forward to seeing it again to see what I missed.
There are certainly more highlights for me than negatives. I enjoyed 95% of the film, with only a few things not sitting well with me. That said, I'm also excited to see what a non-Bay directed film would look like. It has been 10 years. Hopefully Bay keeps his promises this time around and only stays on as a produces while someone else directs. He can check off the designs of the robots to make sure everything fits in the franchise, but hopefully he does stay out of it for the most part. It's time for a change up.