Pros : Easy to use and also very fast and effective, especially on dichroic glass.
Cons : None really, other than this being a somewhat hazardous material. You must wear gloves!
Other Thoughts : Interestingly, a simple Sharpie marker makes a great stencil. I just marked a pattern on dichroic glass and rinsed after a moment or two and PRESTO!. The ink resists the etching cream just like a stencil.