Note that this review contains spoilers so I would not recommend reading it if you haven't seen the film yet.
I really liked this film a lot! The setting of both the town of Norville and the kingdom of Camelot was really cool and genuinely felt mysterious. I didn't even really mind that the time travel was all fake, to be honest. The explanation for why it was fake made total sense and didn't feel like a cop-out like the two sequel movies from 2019. I did kind of like the twist at the end (both of them, actually), especially the one where no one knew where Merlin came from or who he was. I didn't really like how ridiculous they made Merlin (or the fact that King Arthur has "posh king" jewelry like a rapper would have lol)
The villain was excellent! I loved how creepy she was and how she could shape-shift into a dragon. That Black Knight was genuinely pretty spooky too once he had his helmet off, and I would have liked to see more him!
I liked how they dove into Shaggy's ancestry for this one. It's cool to know a bit more about his family, even if we didn't get to meet any additional members. I assume the Camelot ancestry was on his mom's side though since she gave him the amulet. His dad's side must be the one with the werewolf curse we saw in "Moonlight Madness" (The Richie Rich / Scooby-Doo Show) haha.
Velma was a lot more likeable in this film, IMO. Even though she was still skeptical, it wasn't over-the-top like it has been in the past three films. I didn't really like the characterization of Daphne though. Her quirkiness felt incredibly forced to me, especially how she thinks reality is a simulation. The writers of Be Cool and Maxwell Atoms did a good job, but the writer for this film really just didn't capture the quirky Daphne I like.
Lastly, I felt like all the references were super cool. The ones I caught were the airport guy's name being HB, the gang being from Crystal Cove again (interesting they seem to have switched the location in the main canon), Barney Rubble, and then all the flashback scenes we see when the gang is time traveling. I caught scenes from the following episodes: Moon Monster Madness, Happy Halloween, Where's My Mummy?, Zombie Island, Beach Beastie, the A Pup Named Scooby-Doo and Be Cool, Scooby-Doo! intros, the first episodes of Scooby-Doo! Mystery Incorporated and The New Scooby-Doo Movies, "A Night Louse at the White House" from The New Scooby-Doo Mysteries. A scene from Captain Caveman and the Teen Angels is also shown. I thought it was super interesting how much they made Thundarr the Barbarian a part of it! For those who haven't seen the show though, it's actually pretty dark and is nothing like how silly it's portrayed in the film.
Overall, I found this to be a really good movie and as good as Happy Halloween, Scooby-Doo!