I was one of the people who waited for this since the beginning, and boy, it did not dissapoint.
The story was really good, I loved all the storylines of the characters, with Fred and Velma's being the most interesting. The first half was setting up the characters and stuff, and I was like "Is this it?" But no, it wasn't. When the second half of the episode starts, you're in for a big treat, especially if you're a Scooby fan. There are a lot of references, some even hard to notice. But they don't rely completely on references and tell a great story.
The acting was great. Really, really good. I wish some moments with Daphne and her rival and the 49er were told better, but the acting was amazing overall. The settings were also good, they definitely did some great work.
Overall, this was really worth the wait.