Glass dildos are great! They all get really slick with lube, can be warmed (or cooled) in water, and are totally easy to clean. Texture wise there are all sorts of options, like the nubby you pointed out, or ridged, or smooth varieties. What works best depends probably more on your personal preferences than any one design factor.
I would say that if you like softer and more bendable materials generally you may find glass to be somewhat of a letdown, but if you like firm pressure glass is definitely where it's at.
We have a couple of glass toys (a plug and a few dildos) and really like all of them, not too mention they tend to be a little more fun to look at. Personally we like a mix of glass and silicone toys, because they each have things they are better at, but if you are curious about trying a glass toy out for the first time, definitely go for it. You will probably like it.