I had my Z2 for a week or so and these are my impressions about the phone. Please note that I waited ages for this phone and really wanted it to be my next phone. I embraced the phone with a Sony fanboy attitude, certain of the Z2's superiority in every field. So not making some rage samesung fanboy comments here.
The good
Battery performance was really good for me at least, and stamina mode was incredible. The camera was solid and fast. Big thumbs up for Sony for including the hardware camera button.
I found the exterior design beautiful. However the phone wasn't as sturdy as I had expected.
I liked Sony's Android skin and overall I was very impressed with the speed and performance of the phone.
Unfortunately though the phone had couple of features that ruined it for me.
The screen
The screen wasn't bright enough to be honest. It was difficult to see the screen outdoors, even when then sun wasn't shining. But with that I could have lived with. It was the bloody digitizer shining trough the screen that killed it for me. I could see it indoors if the lighting was any brighter than normal "house lighting", I mean at a buss, at a mall, at my school and so on. It was just way too visible, especially against light background. But it got even worse in the sun. Normally I could see just a grid. In the sun I could also see these little dots in horizontal lines. The dotted line would "travel" up and down the screen as the ray of sun hit different parts of the screen. I compared the screen to several other phones wich none of had similar issues. I can see a very faint grid under my iPhone's screen when the screen is off and in direct sun light, but nothing like Z2.
Please see this thread as I'm not alone with this:
http://forum.xda-developers.com/showthread.php?t=2738585
I find it incredible that people can live that screen.
Overall sound quality
Right off the bat I thought the speakers were decent. I wasn't expecting much anyway. Then I noticed, that with higher volumes the phone would sort of vibrate. I could feel the vibration on my finger very clearly. Now this wasn't issue either since I never use the speakers of my phone anyway.
Then I noticed that the earpiece is pretty weak. Not very clear sound compared to other phones. During a call I would also hear almost constant static noise. I'm willing to admit that perhaps my earpiece was somehow defect since I read reports about crystal clear sound while speaking. But during a call I could, again, feel this annoying vibration on my finger as the other person spoke. It seriously bothered me and gave a cheap feeling.
Last but not least, microphone quality. I recorded some videos and WhatsApp sound messages, and the sound quality was very disappointing. It was weak and almost like muffled. Whats the point of having a good camera if the microphone is sh**? I also looked at some sample videos someone had shot at a concert, and the audio was just awful.
The verdict
Overall a great phone but with too many unrepairable issues. Definitely not worth over 600 for me.
