Yes worth it, use plenty lube, don't let it stick to the paint & for christ sake if you drop it don't use it again as it will pick up everything it touches on the ground.
Run your hand over a section of paint for a before & after result.
Keep 'turning' the clay for a clean surface, once you start to use it you will catch on quick enough.
I used this one but there are others about.
Hope it helps