[Xperia Z3 Compact Q&A, Help & Troubleshooting] romcio47:
As a guy who is now waiting for his new LG G6 I can say some final words about my Xperia Z3 Compact before I sell it:

Reception

- very nice, no problems with the signal at all.

Screen on time

- non-root, bluetooth always on, mobile data always on, streaming with spotify, Android Wear watch always connected - ~4,5 - 5 hours. Android Marshmallow killed the Sony's wonderful STAMINA mode so the SOT is just... average.

Performance

- very, very nice. Never had any problems with the speed AS LONG AS THE PHONE STAYED COOL. What do I mean?

The heat...

- because the components are arranged in pretty DUMB way (I'm an electronic's service specialist and this is my opinion), the CPU and other heat-generating components are right under the display, then there is PCB and then the battery. On Marshmallow the phone tends to overheat pretty quickly and it's hard to cool it down sometimes especially when you are in urge of charging the phone... Good luck... This brings me to:

The GPS

- AWFUL. AWFUL. AWFUL. Sony messed up the construction of the phone, the GPS antenna connectors are not properly touching the copper plates on the antenna itself which causes the GPS work like S.H.*.T. . Sorry for the offensive words but imagine Google Maps telling you to turn left... 300 meters after the corner. Your marker stays in one position, the phone is searching for the GPS, the position changes and the marker freezes again. Repeat it infinitely amount of times. I fought with this crap for more than a year now, just got the phone from the Service Center, they changed some parts and the problem remains the same so I decided to sell it and try another manufacturer.

Overall battery life

is pretty good on MM as long as you have a brand new device which should be cheap now. On KitKat it's MUCH better but you lose some functionality.

Camera and photo quality

- NO. Absolutely NO. After SIX YEARS of being loyal I will NEVER choose Sony over any other smartphone manufacturer as long as they will keep their VERY aggressive post processing in photos. I miss my Xperia T which took much better photos in terms of... pretty much everything except the resolution. Many people may disagree with me but check the tests. Sony tends to squeeze much more pixels in the same sized sensor as their other 12-13-16 megapixel sensors which are much better in LG, Samsung, Xiaomi phones etc. Every time new Sony flagship came out, I checked the camera quality by myself f.e. in the store or with help of my friends who bought the specific model. Compared to Z3C it's slightly different, but the overall problem remains the same. It's really sad their sensors are the best on the market but their smarphone's cameras are just... meh. And don't look at DxOMark results, look at real-life tests, GSMarena photo comparison tool etc.

Glass cracking, glue coming off

- this problem affected early Z3C models from 2014, in 2015 they mostly fixed this problem. The same comes to glue comin off. Mine never had any problems at all, the phone was always sealed perfectly.

If you want to be loyal to Sony, buy Z3C, but if you're still not sure... think twice.