I recently upgraded to a k850i which i have also written a review on.
I started with a 750 and decided on my birthday to upgrade to the 800 which a friend of mine recommended to me..
There are again a lot of haters of this phone all because it has a joystick/nipple in the middle of it, which apparently for a lot of people keeps going wrong.. Ive had mine for a year and have had very little problems with it if any!
The picture quality on this phone is superb and out performes many digital cameras, i personally thing sony have 'hit the nail on the head' with the cybershot series. I would 100% recommend this phone just for the camera, as that is the best part about it!
The sound is very good the speaker is excellent when playing music or making a call.
Ufortunately i do have one gripe about this phone; i havent got the best memory and sometimes forgot to lock the phone, sony for some reason that only they will know put the internet button right next to the back button, so pressing back to the main screen in a rush not looking the internet is on and half your credit is in the bin!
Otherwise i think the phone is well priced for what it is and again recommend getting a mem card for it!
Unfortunately sony either make great music loads of memory or great camera no memory at all!
Get a card and your problems are solved before they've started.