'Scooby Doo and Guess Who' sounded very interesting and really liked the idea of the gang solving crimes with various guest stars (a mix of real life celebrities in the film, music and sporting industries and popular characters). So a more modern version of 'The New Scooby Doo Movies', loved that show as a kid and quite a lot of episodes and guest stars hold up but some episodes and guest stars don't quite do it now. This show turned out to be mostly very well done and at its best great.
"The Haunted Horrible Hospital of Dr Phineas Phrag" is one of those great episodes. It is not quite as great as "The Last Inmate", but it is one of the best episodes of a more settled Season 2 and proof in my view that 'Scooby Doo and Guess Who' is worth sticking with if one was put off by its fairly slow start. Loved the idea of the setting and the villain and "The Haunted Horrible Hospital of Dr Phineas Phrag" delivered on both. Had not had much knowledge of Kristen Schaal's work prior to this and the episode didn't put me off seeing her again, so that's a good thing.
My only issue actually is the over obviousness of the culprit's identity.
Other than that the episode is great. Schaal is a lot of fun as a guest star. She comes over as very sassy and with a good deal of energy, had no problem with her voice. She interacts very entertainingly with the gang and is well used, not dominating too much (unlike Steve Urkel for example) or underused (from memory Christian Slater). Shaggy and Scooby are their usual delightful self, being as hilarious, charming and endearingly goofy as ever.
Absolutely loved the setting, which is one of Season 2's freakiest, reminding me a little in atmosphere to Season 1's "The Nightmare Ghost of Psychic U" (except a much better episode). Likewise with the super creepy villain, who has a very unique and nightmare inducing design. The writing is fine, with a lot of amusing humour, and the mystery is a lot of fun and creepy. It doesn't come over as too simple or slight, neither does it try to do too much. The gang interaction is spot on and the character writing is well balanced and faithful.
The animation has a lot of atmosphere, rich colour and even richer attention to detail. The music is dynamic and groovy, also loved the modern spin on the iconic classic theme tune for 'Scooby Doo Where are You', although it is too short. The voice acting is very good, with Matthew Lillard nailing it as Shaggy.
Concluding, recommended highly. 9/10.