[anmb]

just bought my lumia 820 on 24 month contract
i love the look and the way some things work, plus wireless charging but:

1. cannot change individual tile colors, only all of them
2. phones usb wont connect to xp, struggles with vista, dont have windows 7 or 8
3. no file browser on the phone
4. took days to customise to my own ringtone - I think it was changing the mp3 genre to 'Ringtones' which finally got it to work
5. still havent worked out how to customise my own text alert - dont think this is currently possible

i may not be the 'sharpest tool in the box' but on my previous n8, all the above was dead easy but the 820 its so difficult.
potentail yes but frustrating too

[Kebero]

1. That's just how Windows Phone works.

2. I think you must use the Windows Phone application for XP or Vista.

3. See #1.

4. I personally use an app called Free Ringtones, which eliminates the hassle.

5. See #1, I think.

[eReS]

ad 4.
Nokia Ringtone Maker for Windows Phone 8 on Nokia Lumia 820 - YouTube

[EDIT]
actually you do not even need any application to customize ringtone by adding your own mp3 file - just go to settings -> ringtones+sounds -> press "get more" link - there is an info how to transfer mp3 to your phone as a ringtone - mp3 file just cannot be bigger than 30 MB