First, some of the units are coming with the hinges loose. This causes the screen to dangle when the phone is turned upside down. The second problem is that when the phone is held at a certain angle, the screen will snap shut if it is open. Finally, some of the G2 units are arriving with half of the 4GB of memory promised. Whether or not it is part of the reason for the mix-up, the G2's twin, the HTC Desire Z, comes with 2GB of memory.
If we have learned anything this year, it is that the more complex smartphones become, the more problems you will see at launch. And with the number of Android models multiplying rapidly, it is no surprise to see some bugs and defects out of the box. It is unknown how widespread these bugs are, but as the next few days go by and more G2 units are unboxed, we should have a better idea of how many phones are affected.
T-Mobile G2 Specifications
source: Engadget, Xda-developers