Yeah I've used it for models, bowls (until I realized that triangles seem to glide better), and obscure surfaces. For example:
This surface doesn't technically exist as a discrete surface, so it looks awful when made with brushes. But, q3 seems to do a really good job visually when using patch meshes.
This one you can see the patch mesh subdivided in radiant... the textures were a little buggy (twisted) because of whatever and I never ended up polishing this jump. But, essentially the entire length of the "roller coaster" is just a very long 3D curve drawn in space, which some code converts into a set of points on a NxM patch mesh. Then, some other code writes that patch mesh to a .map file, dividing the NxM patch mesh into several adjacent PxQ patch meshes when necessary, where P and Q are both odd integers <= 15.