Pros : Much much easier than cutting small circles by hand.
Cons : Made in China, had a few flaws. Smooth plastic base has slight hump in it making it impossible to cut glass without it sliding around. I remedied this by gluing a piece of that rubbery shelf liner stuff on the base. Now it works great & my glass doesn't slide. Also the ruler markings on mine were printed off center making them useless. Doesn't matter since I covered it up with the shelf liner anyway.
Other Thoughts : Even though it has a couple of flaws it's worth buying if you cut small circles often and you're willing to do a simple modification.