(Disclosure: I did proofreading for Madhouse before its release. I do not get any compensation for sales of the game.)
Setting and Theme
Madhouse provides an interesting setting in the town of Lakeshore as a whole – a standard 'town with a troubled past' out of any good horror film – and the Lakeshore Asylum as a whole. There is no reason that groups can't use the rules and themes for their own local or custom settings, however. The game does ostensibly focus on the Asylum as the primary location, but provides a good history of the city itself (as well as suggestions later in the book), enough to give groups a good base to work from if they wished to take their stories outside the titular madhouse.
Thematically the game uses a variety of horror genres, from cosmic to creature feature to slasher and, of course, mental illness. That last one will be a sticking point for some groups, as the game does heavily use the setting of a corrupt, twisted, and terrible asylum where most of the characters are patients. The asylum is a dark, messed up place under the control of someone twisted by eldritch knowledge and a part of the horror element is being trapped within its walls.
Madhouse uses a d10 system that's rather quick and easy to learn. Though I will admit I have experience with similar systems, so that possibly helped. The system seems suited for lethal or non-lethal combat, depending on the severity a group wants, although given the horror elements many stories will become very dangerous.
Player characters are simple to make, with no real classes per se. Players pick their concept, get a pool of experience to spend on their various character aspects. Being sane is a disadvantage, as it prevents the character from interacting with certain game mechanics.
The closest thing to character classes that Madhouse has would be the Disorders: game representations of a character's mental illness (assuming they don't have the "Sane" Flaw). There are five of them broadly representing both mechanical niches or foci and certain mental illnesses. Mechanically they provide both good and bad things. The fact that mental illnesses are used in this way may be another sticking point for some, and I would not recommend Madhouse to those players.
Madhouse is, overall, an interesting game and one that I'm looking forward to running at some point. Between the horror genre, asylum setting, and inclusion of mental illness mechanics this game is not going to be for everyone. I do, however, highly recommend it to those looking for a good and easy to get into horror RPG.