Well I've got the Nokia Lumia 520 which is nearly 2 years old running Windows 8.1 Cyan. I love it and the camera is great and takes really good photos.
Since it upgraded to 8.1 though the only thing that annoys me is the way without me doing anything it will take itself off my preferred Wi-Fi, which is my home router, and connect to BT FON, so I can't do some of the things I want to do.
It's not as if I go out and need the range of open Wi-Fi I'm in the house all the time.
Apart from that I still really like the phone and will get another but hopefully higher up the model line.