there has not been any of the stability issues with the k800i that has bedevilled the k850i, it is considered generally reliable and easy to use.
the main cons are:
- a bit brick-like and heavier than most... although that is not necessariy a bad thing from a camera point of view, and also it's because it is metal-framed which makes it more sturdy and can survive physical abuse better than most
- the camera lens cover slides open too easily, a lot of people have been taking pictures of the inside of their pocket
- the joystick design of the K-series is notorious for being a dust trap... this can result in them sticking or not behaving and developing a mind of their own after a while
- otherwise a great camera-oriented phone, and as it's on its way out, you can get it fairly cheap now, expect to pay no more than £70-80 on a locked PAYG