Not too bad by Rand standards as it does have a plot, characterisation, a believable antagonist, a love story (if you're a sadomasochist who likes borderline non-consensual sex, but there you go), and the Message isn't too overdone. Howard Roark is a bit of a jerk to be honest and 'he never changes' says one character - not sure that's supposed to be a good thing you know. Dynamiting Cortland because the design was changed? Well no. Just think: Roark would probably have physically attacked Charles Jencks if he'd met him. Then maybe at least he'd do some time and how do you like your Objectivist principles when you're sharing a cell with a drug dealer from the Lower East Side, eh? (n.b. it is possible to infer dangerous situations in prison without making jokes about r*pe. I just did so.)

Roark is generally held to be based on Frank Lloyd Wright, although I suspect he's also partly Wells Coates (1895-1958), a Canadian architect who designed innovative public housing but found his designs co-opted by better self-publicists who then changed them. His best known work is the Lawn Road (Isokon) Flats in London. Coates believed that "a rational, scientific, formulated approach to architecture" was needed, which sounds a bit Randian but not in a bad way.
Possibly this was Rand at her least unpleasant. Her description of 'looters' generally refers to people who make money without doing the work - speculators and the like. That she wasn't actually anti-capitalist sticks in the craw for many people, but there you go. She wasn't.