This was just a mediocre episode for me.
Location-wise, this episode had a really spooky feeling setting in the museum. I didn't quite understand why the gang was in Ricky Gervais's apartment, but maybe I just missed that part.
My biggest complaint was that Ricky Gervais seemed to completely overshadow the gang. Most of the lines in this episode were him making jokes, none of which were particularly funny. The only two I enjoyed were him pointing out that Scooby was just saying his name, and the reference he made to Laurel and Hardy ("Ollie, that's another fine mess you've gotten me into."). I thought it was cool that they called back to The New Scooby-Doo Movies.
It was very easy to figure out who the villain was. I liked the Cat-Headed Mummy as a villain, and it was fun that they referenced "Scooby-Doo and a Mummy Too" with his catchphrase being similar to the original mummy's "coin!" and a jewel/valuable item being hidden inside a statue. It was also interesting to see almost an exact replica of Professor Hyde-White from "What a Night for a Knight."
Side note, I thought Fred's catchphrase officially being made "Hold the phone! was a bit weird, especially in the opening title where they say the name of the guest star.
Overall, a mediocre episode mainly because Ricky Gervais had too big of a role in the episode. I'm hoping we can get back to the kind of dynamic we saw in the previous episode with Sherlock Holmes in the next episode.