No complaints. It doesn't break as easily either as the previous versions and most phones out.
My friend has the HTC One, but there's 2 con's about it.
1. You can't remove that back, meaning no extra battery.
2. There's no SD Card port. So you can't extend the battery.
I need those 2 things to even survive without a phone, that's why I went w/ my Galaxy S4.
I have 2 battery's full charged everyday, so when one dies. I can simply replace it with another unlike the HTC One and it has a pre-installed 16GB into the device, and I have a portable SD Card which is 16GB's also. Making it 32GB in total.