I've been using my Nexus 7 with the new 4.4.2 update for one week now and I've noticed a few issues/concerns -- I should emphasize that I use the N7 daily, and for some hours at a time.
1) When the N7 is turned off and charging, I used to be able to do a quick press of the power button to see the charging status; not so any longer. A quick press does absolutely nothing, and holding the button just a split second too long simply turns on the device.
2) Boot-up process seems to take forever, including the UCCW and Minimalistic Text widgets that I have on the homescreen.
3) Battery use has taken a huge hit; when I check the usage I see that the screen is using 65%. I have no idea where this is coming from since I'm using the same screens, widgets, etc. since before the update and I have the screen brightness as low as it will go.
4) WiFi comes and goes a lot; I'll be checkiing the Play Store or some post in G+ and will get a msg. that there is no WiFi connection. Never encountered this before the update.
5) I use the Swype keyboard with a stylus that worked near flawlessly before the update. Now, I get garbage letters and random spaces instead of words. Though I just read today that Swype has an update that deals with KitKat compatibility issues, so hopefully this one has been resolved. (I hope so because it's been frustrating as all get out to be typing garbage.)
6) And lastly, I'm really ticked off that App Ops has been eliminated in 4.4.2. I really appreciated the ability to monitor -- and disable -- permissions on all my apps.
That's the immediate stuff that comes to mind.
Anyone encountering the same issues (1 through 4) or have you seen others?