The Windows 8.1 DP runs good but there are some issues present like high battery usage, random battery drains within a few minutes, overheating, resuming/loading problem, bugged cellular data and disabled internet sharing (so far these are my problems when I used DP on my 1520). I would suggest you wait for official Cyan to be available to you. Also, as of now you cannot update from DP to Cyan directly (assuming you are on DP and Cyan is made available). You'll have to use Nokia Software Recovery Tool (assuming your phone is a Lumia) to get Cyan, but that erases all your data so it's quite a hassle.