The proportions compared to a classic blackberry seem terrible for typing ergonomics. With a Blackberry, the overall device is closer to a square and the keyboard is basically the bottom half of the device. With the case, the keyboard is like the bottom 20% and it seems like the weight of the rest of the phone would be constantly trying to leverage it out of your grasp, especially since blackberries were like half as heavy as a modern smartphone.
The listed weight is 62-65g so its not appreciably more dense than the phone in my estimation, certainly not enough to greatly shift the center of gravity.
