Having worked with both VK and real keyboards, real is always better, whoever opposes this is lying. But they may not be lying if they tell you the virtual keyboard is sufficient enough for daily use, especially true once you work with screens >3.2" size.
At 3.7 inches of real estate, I don't mind a VK and not having a real keyboard will keep the price down. I will reconsider, should the G1 ever have it's real (and high end) successor.
Being a heavy user, a long time ago I accepted the truth regarding battery life and monday through friday, you can find a usb cable in my pocket, no matter what phone I'm using. As soon as a breakthrough in battery tech allows > 2500 mAh capacity, I''ll reconsider until then, I expect the worst from all phones.
It's all speculation without knowing a price but the N1 seems to be a affordable high end set, which is exactly what TMO needs.
For my next phone, rhe only 2 criteria I will not compromise on are TMO 3G compatibility and speed. After that, my preferences are Android OS and capacitive touch screen. N1 fits like a glove, for me at least.