Here's the thing...glass toys seem to be best for g-spot use (or anal, I suppose, even though I haven't used it that way personally), because they are so inflexible, they put enough pressure on the g-spot to have that type of orgasm. While you can thrust with some of the styles of toys, I don't really love it as much as using something flexible for thrusting.
I personally have a VERY hard time having g spot orgasms in general, regardless of toy or partner, so my glass toy is one of the least played with toys in my toybox. On any given day, I prefer thrusting or vibrations. Since the g-spot issue makes me cranky, I don't do it often.
If you like g-spotting, I say GO FOR IT! If you're like me, maybe not so much.
If you are looking to try g-spot play, glass is an excellent tool to try it out. I would advise to go for one of the less expensive ones (luckily glass can be pretty inexpensive) and give it a try. There's not much money to lose!