Now that some days have passed I feel safe to say this, BIG improvement with my battery life, I'm using a 920 and with the first release of 8.1 DP the battery life was awful, I had to charge my phone in the morning, then charge it again at 5 or 6pm and then sometimes at night again, so 2 times a day and sometimes even 3, now I'm able to charge my phone at night and use it until 8 or 9pm of the next day, I was thinking that it could have been a faulty battery but now I'm happy with my 920 again, I don't need to carry my charger to college anymore. And from other bugs, I really didn't have them, just noticed that everything seems faster (except nokia cam which still is very slow to open); Facebook beta flies on this update, just gotta remember not to close it (kinda hard since now I'm used to just swipe down to close apps).
Delay while launching Cortana no moar!. Also I'm not sure but it seems like Cortana has new animations.
That being said I kinda feel there is no reason to upgrade to the 1520, Icon or 930 just yet, but then again, I'm weak...