Ok so i recently bought a S5 900F, one thing I've noticed is that 4K video from the S5 isn't as good as that from the Note 3, which i also had. For some reason on the S5 the colours look slightly over saturated, the note 3 looks more natural. Also video sharpness seem to be slightly better on the Note 3 aswell, I have a 4K monitor so can see the difference, which doesn't show on a 1080p screen . The most annoying thing i've found recording in 4K on the S5, is that it has a tendency to skip if the lighting conditions suddenly change quickly, doesn't do it all of the time but when it does it spoils the video, I've tested another S5 and it does the same thing so it's a camera firmware issues that maybe fixed in the future, the Note 3 doesn't have this problem at all both where recorded on the same 64GB Samsung class 10 card. Tbh i quite disappointed with 4K on the S5 if anything it should be better than that of the Note 3 but atm it isn't, as the S5 is still new i may get sorted out with future fixes, but as it stands the Sony sensor does a better job atm than the Samsung sensor in 4K.