Overall, a very impressive effort. Here are a few of my thoughts:
Styling is modern and crisp except for the windows in the rear doors, which look too much like the last generation Blazer's and do not match the rest of the styling. The taillights are perhaps too big, but overall a very clean look. HID headlights would have been nice on the LTZ.
The interior is a huge improvement. The style leapfrogs the competition. The center stack has an attractive symmetry, but the radio is too far from the driver and too low. Steering wheel controls need to be standard now. The climate control system is especially low, though that will not be a big concern for units equipped with climate control. The protruding center stack appears to preclude a center passenger. Perhaps models without a center console will have the center stack flush with the dashboard? The downside would be an even longer reach to the controls.
The additional length and weight are not good. The Tahoe can handle the additional length, but it would be bad if the same thing happens to the Silverado or Suburban because they would not fit in a lot of garages. Additional weight is expected for the additional features, especially the safety features, but 400 pounds is a lot.
With rack and pinion steering now instead of recirculating ball, steering feel is probably much improved. The 4-speed transmission is disappointing, but not having a new 6-speed transmission is one less thing to go wrong on a new vehicle. The existing 4-speed unit is not particularly smooth though. I'm surprised the 4800 engine is still around. Why is it still here? Does it make sense for GM to continue to develop it?