When it comes to functionality, the K850i is so cutting edge you could shave with it. It has HSDPA 3G, Edge, GPRS, an FM radio, Bluetooth 2.0 and A2DP wireless stereo playback. It lacks Wi-Fi, which frankly is no surprise - it isn't, after all, trying to be a smartphone.
On board storage is a reasonable 40MB but the card slot will take either Memory Stick Micro (aka M2) or Micro SD to the tune of 4GB. So at long last we get a dual-format memory card slot on a Sony product. About time too, though the company insists on bundling a 512MB M2 in the box.

So cutting edge you could shave with it
The basic handset, menu layouts and graphics will be familiar to anyone who has used a Sony Ericsson within the last year or two, though it does introduce a few novelties that mark the K850i out as a landmark product. The most obvious additions are the Media Centre and the three-touch sensor soft-menu keys that are as much part of the screen as the keyboard.
Also new to the Sony Ericsson user interface is the four-way, oblong control - often called a 'D-pad' - that now forms part of the keyboard and encloses the 2 and 5 keys. It's a playing card-shaped raised plastic ridge which increases in height at the four compass points. You press the ridges to navigate, press the middle soft-menu key to action. Yes, the the activation key is outside the pad not inside it, which takes a moment or two to get used to, but once you have you wonder why nobody has thought of this before. It glows a nice shade of blue too.

A new take on the old D-pad navigation control
The K850i comes with an all-in-one media player to manage your music, and display videos and pictures. The Media Centre interface is similar to the Walkman 3.0 software and is straightforward to use. The player supports MP3, AAC, WMA and MPEG 4 and is accessible directly from the dedicated Media Centre key adjacent to the Answer key. The music player has a range of EQ settings, most of which work, but avoid the one marked Stereo Widening. It widened the sound all right, but Bruce Springsteen's vocal on Radio Nowhere fell through the vast chasm left in the middle.
COMMENTS
K810 Torch
If you're looking for a torch for the K810 (might work with K800 too - I don't have one, so I can't say) then visit esato.com. It's a website that reviews mobiles, etc, but specialises in SE.
Do a search for k810 and torch, and you should find that there's a small java program that uses the auto-focus red light as a flash.
I've been using this since upgrading from my old K750 and discovered that I used the torch a lot more than I realised, and have been happy with the results.
compared to the K810...
...there doesn't seem to be much of interest about this phone. There are 3 things about my K810 that the K850 addresses and that is the battery cover (everytime i slide my phone into my pocket the battery cover comes off), the flash-as-a-torch (i had this on a w550 and it came in useful soo damn often i was gutted when i upgraded to the k810 and had already given away my W550) and the sliding camera lens cover has been removed (opens at every opportunity on my handset). Any joystick jams i have had on the K810 have been fixed with a spray of air. The next phone i go for will have wi-fi and a torch function.
@Mark
Lets see:
"It lacks Wi-Fi, which frankly is no surprise - it isn't, after all, trying to be a smartphone."
It is not, and was never intended to be, an N95 beater. The game can't be over if the players aren't even in the same league.
BTW: looks as a great phone to replace my old trusty K700i
Camera response time..
Matthew, in answer to your question the 850i takes about 1.5 seconds to auto-focus and take a picture, either with or without flash, and maybe a further 2.5 - 3 seconds to process the image and let you take pic #2. It's faster than many cameras I have used, and certainly faster than my trusty old Nikon.
This reviews is missing the key piece of information
The key piece of information for camera phones is the length of time required to take the damn picture! My old Samsung took so long, photo's always ended up with people moving away.
Any indication of time between shutter-button press and image capture? Also, how long does it take to process the image, so that the camera is ready to take the next shot?
