Typing is fairly fast.
What I don't like about USB keyboards is that the backspace button functions slightly different. On the iPad deletion speeds up, when it is kept pressed, but for USB keyboards, it always stays at the same speed, which makes it quite slow when deleting longer passages.
Anyhow, when typing on the virtual keyboard, I revert to my own 7-finger typing system. It works fairly well, definitely more typing errors then with an actual keyboard, but still much faster then then 2 thumb pointing circus, when using the iPad in portrait mode.
The touch of glass has never bothered me much, besides from the sound of fingernails hitting the glass. The nails really need to be cut short, or typing becomes a noisy task. But my tip segments are vertical when writing, perhaps if they were bend less, the problem would alleviate itself.