I had the 910....the buttons were not soft rubber cells like the 990, but still 9 or 10 keys accross. It will take a little getting used to. I really started to get good in the graffiti area, it became faster than trying to type it only to backspace a few keys because some of the text never took (I didn't press hard enough a few strokes back)
at least on the 910 when you took the keypad off you had twice screen, not with the 990. Plus the jog dial was a 5-way, meaning you could pull it foward or press it back. The 990 is a 3-way only I heard. I still would have gotten it until I found out it's not 3G here in the states, only in Europe. (bummer) I ended with the HTC Tytn...(Cingular 8525 cousin with video conferencing)