I immediately noticed differences in the appearances of the characters between this movie and the old series:
- Some of the characters' clothing was modernized: Freddy was no longer wearing that goofy little ascot, Velma was wearing a t-shirt and shorts and only ankle-high socks, Daphne was wearing a short-sleeve bodysuit, shorts and no pink tights. (Though the character's color schemes were pretty traditional.)
- The characters had whites to their eyes. The old characters had no whites, just irises floating in skin tones.
- The characters had a lot more shading and shadow. They looked a lot more three-dimensional.
- And perhaps as a consequence of these other changes, Velma had a noticeable bust, and Daphne had a very noticeable chest. I can't tell you how odd it is to be staring at Daphne's breasts.
I found the plot more satisfying than the previous movies Scooby Doo on Zombie Island and Scooby Doo and the Witch's Ghost; it was more true to what I consider to be the Scooby-Doo tradition.
The movie was also notable because it had love interest for Scooby and Shaggy. Or at least, notable for having love interests that weren't pizza. The psychedelic-60s-pop-song-pastiche "Groovy" was probably the highlight of that romance.
While I'm on the topic of Scooby Doo: this news story says that in the live-action Scooby Doo movie, Shaggy's girlfriend is named Mary Jane. Is this not tantamount to an admission that Shaggy is a drug-addled dope fiend? (I know that you've all seen the web pages arguing that Scooby and Shaggy were tokers, but this seems to be pushing things even further.)