It works fabulously with my Apple Powerbook. I'm able to synchronise my calendar and address book over Bluetooth, with only a few bugs that are being worked out. I can use the phone as a remote control for various applications which is proving to be very useful. And bravo to Ericsson for using an open standard for putting together custom HID plugins. Lastly, Quicktime has a built-in export profile for 3G media files so getting video and audio in a size-appropriate format is a three-click maneuver.
The little J2ME interpreter is pretty speedy for a phone, but unfortunately not fast enough to run a playable NES emulator. I've got an SSH client on there, but at $0.03 per kilobyte of data transfer through AT&T, I can't imagine I'll be using it much.
It includes an FM radio since it's a trivial energy-drain on the battery, but the hands-free kit cords double as the antenna and won't work without which is a shame since they are constantly tangled. I intend on picking up a wireless Bluetooth headset soon. The white LED flash doubles as a decent flashlight, and the camera has a variety of effects available including a three-shot panoramic view.
All the reviews I read claimed it gets horrendous battery life. I managed to drain a full charge in a little over twelve hours with heavy bluetooth usage, but when I just make a few calls and check the calendar once or twice I can stretch it out to at least two days, maybe three if I really took it easy.
All things considered, the K700i is a fantastic phone with a great many features all packed into a little tiny case. It was definitely a good buy.