Here is my post from the Developer Preview forum:
Update (05/19): I had rolled back to 8.0, installed the new *.1417.0047 firmware then updated to the new DP release *.12382.878 on the 13th.
1. Didn't suffer from the 3 second screen wake delay for 6 days and then it came back. Only happens when WiFi is on.
2. My WiFi reception is better on 8.1 with the new firmware, but still not as good as on 8.0 with the new firmware.
3. No more purple hue, though I have tweaked the color profile.
4. I still sometimes get false battery readings, mostly when playing games while connected. A scenario was: my battery was at 90%, plugged in my phone, started to play a game, and after a couple minutes I realized the battery icon was showing that the battery was fully charged. After playing for a while, I closed the game, removed my phone from my charger and went to do something else. When I took the phone off the charger it was at 100% and about 30 minutes later when I came back the phone was at 93%, from no use. So I plug it back in and it does the same thing - straight back to 100%. So I restart my phone and it goes back to 93% and continues charging. Never happened in 8.0.
5. It doesn't overheat with simple tasks anymore.
Original post:
1. The lock screen takes about 3 seconds to power on after pressing the power button. Never happened on the first day, started happening frequently after the first day.
2. Extremely poor WiFi reception. I lose signal even when i'm relatively close to the access point. The WiFi icon reading also isn't accurate.
3. Purple hue screen in automatic brightness mode. My display goes purple, especially in grey areas such as the keyboard, when the display goes into the very low brightness mode while using the automatic mode.
4. False battery meter readings. I charged my phone to 100%, took it off the charger, took a 2 hour nap and the battery reading was at 90%. I soft reset and then the battery reading was at 100%. 10 minutes later with no use it was at 98%. 30 minutes later it was still at 98%. Another 30 minutes later with no use, 97%. 1 hour later with no use, my phone got really hot and went down to 80% - when I unlocked the phone I got a Loading/Resuming screen for the start screen.
5. Overheating with simple tasks. Even just using the messaging app will cause the phone to get warm. Playing games such as Subway Surfers, or taking pictures with the camera causes unbearable heat, after 3 minutes of use. Even just browsing the store heats up the phone.