I've read some other reviews of this episode, and know that quite a few people were annoyed by Urkel's antics in this one. But I for one thought this was a great episode, and I'd even go so far as to say that it was one of my favorites of the series.
I've personally never seen Family Matters (the show Urkel was on), but Urkel was an enjoyable character for me. I thought the silliness he brought to the table in this episode was pretty funny, particularly the flashback to Urkel's court case and the ending of him blowing up the Mystery Machine.
The location of the museum itself was pretty cool-looking, and it was perfect contextually given Urkel's habit of breaking things. I was surprised that there was an animation error in which "Coal Mine" was spelled "Coal Minn." I didn't think WB would still make such a silly mistake like that in today's day and age!
The villain being a redesign of the Green Ghosts from "A Night of Fright is No Delight" was kind of cool. I can see how one might think that it was just another lazy repurposing of an original villain, but I think it fit well here and the villain being a "Technomancer" made it different enough that it worked.
I've had a bit of an issue with Scooby seeming a bit off in past episodes. In this episode, I thought this issue was fixed. All the character dynamics were pretty spot on! Velma seemed a tad bit awkward at points, but it was still pretty good.
Overall, while this episode wasn't perfect, I thought it was still very entertaining and a good silly episode to watch when you want to just relax and turn your brain off.
For fun, I'm also going to start something new in these reviews. I'm going to give my overall ranking of the episodes from the series so far, and update the list with each review. Here's where my list, which I'm dubbing the Star-Studded Scoreboard (given this is a team-up series), currently stands (from best to worst):
1. Elementary, My Dear Shaggy!
2. When Urkel-Bots Go Bad!
3. The Cursed Cabinet of Professor Madds Markson!
4. Revenge of the Swamp Monster!
5. The Scooby of a Thousand Faces!
6. Peebles' Pet Shop of Terrible Terrors!
7. Ollie Ollie In-come Free!
8. A Mystery Solving Gang Divided