Painful

I haven't tried that specific glass toy, but I have tried glass toys with "nubs" on them. Honestly, they didn't hurt me in the least -- but, the jelly ones do. I don't understand it.

I LOVE glass though.

Maybe if you move around and find it's too big, but in themselves, they wouldn't generally hurt (in my exp)

Maybe if you are interested in getting glass, try a piece with less texture, and then see how you like it. If you read the reviews for that product, there are a few that found it uncomfortable. I bought this piece when it was on sale awhile back, but I never got around to trying it yet so I can't really help you with my own opinion right now lol

I personally find textured glass painful but I'm sensitive to texture in general. Pair that with harder material and it's a no go for me. However a lot of people find it feels really good. I agree that if you're looking to try glass you should try something smoother first to see how you like it. If you like the harder material, you can always add texture at that point.