They are only unreliable when they are driven carefully by people who don't drive it like a sports car. Rotary engines are incredibly sensitive to any build-up caused by low-rev, low heat driving. Rotary engine sneed to be spin like a top to keep the cumbustion chamber clean...which is why they are actually good for racing.
They do drink oil, however.
Kenny is right, too. They are not that fast. While they say they have a decent amount of hp, they have super low torque.