BGR quotes one user, who said, "Thunder is in no way shape or form market-ready. If Bold was any indication, Thunder won't be ready for at least another 4-5 months. Most of the people who have handled it thinks it's a joke." Not exactly kind words.
But wait, there's more.
Apparently the entire screen moves when pressed, and it will show ripples in the LCD under your finger. The user interface is wonky. It blinks, and there is often a delay between pressing the screen and getting any sort of response from it. It also sounds like the haptics need more work. According to BGR, there are four buttons located under the screen, one in each corner. Depending on how you press the screen, you can get one or all of them to click. Lastly, the accelerometer doesn't work all that well, and the device will go "bonkers" if you move it around too much.
Before you fret about this, keep in mind that the device is months away from being final. There are always software bugs and hardware bugs being worked out during the development process. If the phone were launching next week, I'd say, "Ruh-roh." But it isn't, and RIM has plenty of time to finalize the engineering behind what might be its most important product ever.