I LOVE glass toys. They are certainly among our favorites (with steel, and pure silicone depending on the type of toy). Glass is just amazingly smooth, has such a smooth texture it just glides, has a good amount of heft to it, can be formed to perfect shapes, is non-porous and easy to clean, super durable, retains heats/cold for temperature play, etc... It's just so versatile. In addition, with such a rigid toy, it makes it easy to really hit certain spots with pinpoint accuracy, as it won't bend to conform to your body like some other toys will.
Currently, my overall favorite toy in our toybox is the Lucid Heart ( link
) and it's cheap too!
I always recommend glass toys to anyone interested... try one, and you'll see why!