The camera is still a worthless piece of crap.
White balance is perpetually wrong, and if that weren't bad enough the Auto-Focus is CONSTANTLY RUINING THE VIDEO! It isn't as pronounced when taking photos, but if you're shooting video you're going to notice it the entire time. It's the same problem they had with the One X. I've had tons of great videos ruined because of that worthless auto-focus.
Also, they should have stuck with 8mp and made the pixels bigger. Either let the camera protrude a bit or only make the pixels big enough to satisfy the chassis and MP count. If you have ever cropped a picture, you will want at least 8mp.
Apart from that, Zoe would be more worthwhile if you could adjust the time the videos recorded. 3 seconds is just too short for me. It's like sitting on the couch watching someone else flip through channels. You don't have enough time to appreciate what you're looking at before it changes. Not to mention, the audio should fade in/out. It would make it less jarring.
Blinkfeed is useless if you have Flipbook.
They STILL have not included WIFI, GPS, etc buttons in the notifications menu. Huge disappointment.
Standby power is TERRIBLE!!! Same problem as the One X. The One matched the GS4 in all battery tests right up until standby..... in which it got absolutely spanked.
That said, the GS4 doesn't have everything either. Still crap plastic. Still a rear facing camera (because I like watching my videos from the back??W?T??F??). Still the same boring UI. Low light camera performance doesn't hold a candle to the One and apparently no other phone can touch the iPhone 5's camera in all around photo/video quality.
Just a bunch of disappointments all around. Guess I'll wait until the next gen.