I think the S5 is a beautiful piece of kit. But it's let down by the software. This is one thing that drives me crazy.
I used the S5 for a while and the micro lags and stutters made it feel like I was using a fake china clone.
Take a look at the comparison below. I honestly hope they are able to tweak the UI for future devices. That's the only thing that's holding Samsung back at the moment.
Samsung Galaxy S5 vs. HTC One M8 - UI Performance: http://youtu.be/DChf8nhi2tM
Sent from my HTC One_M8 using XDA Premium 4 mobile app