Performance
Performance is superb no lag what so ever. Antutu gave me 51,576 so it's really up there but I don't know how the individual cores compare to it's competitors with quad core CPUs. I use the balanced power mode most of the time but when you run something like antutu it will automatically switch to performance mode.
Display
The display is beautiful, everything is crisp and bright and has no problem outside in the sun. I do however notice when there is a white backgrounded app it looks like the display isn't completely white, like there is light bleeding or screen burn, maybe it's just my display I'll have to get it checked.
Battery
Battery is pretty good, I've used it casually for browsing a bit of navigation etc and used 50 pct in the day from morning till night. I'm not sure if the battery has been optimized yet by the OS because when I first got the phone it was on 30 pct and I did an antutu test which made the battery drop to 2 pct and then die. Here in China it's pretty common for people to carry round external chargers though so it's not really a big concern for me.
GPS
GPS is great, I can still get a 10 second lock sitting inside by a window, outside the lock is a few seconds or less. Compass also seems to work just fine.
Call Quality
Calls sound much better than my previous phone, but that phone was paticularly bad so it's hard for me to make a comparison. But it's very easy to hear the other person.
Speaker quality
The speaker is certainly loud but the sound quality is not very impressive, I don't often use my phone for music though so it's not a priority for me.
Audio Quality
I have some RHA 750i earbuds that are really good earphones. The MX4 really impressed me with it's capability to drive these headphones well so there's no problems in that department.
The MHA 750i also has a 3 button attachment on the cable which allows for controls on supported phones. On the MX4 i'm not able to adjust the volume with it but I can play/pause which is nice. Maybe I can find some software to get the other functionality like volume or skip track.
Network Quality
4G works great outdoors, indoors it's usually H/E depending on the building but I don't find this phone drops off the network in certain spaces of my apartment like my last one did.
Phone Build/Feel
The phone feels like a premium phone, I have the white one and the one small home button/notification LED looks really sleek but I think I'd rather have the standard 3 android buttons/
Camera
Some random snaps I took:
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Here's some night time snaps just using auto mode.
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Here's one taken in a pitch-black room just using the camera flash
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