How does the Audi A2's Wankel engine compare to traditional piston engines?

I've heard that the Audi A2 has a unique Wankel rotary engine, but I'm not sure how it differs from traditional piston engines. Can you explain the differences?

The Wankel engine was designed to have a simpler and more compact design than traditional piston engines, resulting in improved performance and fuel efficiency. However, it does have a higher oil consumption and may have more maintenance requirements.