Probably my favorite feature of the phone, beyond the camera and screen, is the fingerprint reader. It's very easy to use. It is 100% accurate with my index fingers when holding the phone stable or when it is on my desk and about 95% accurate one handed with my right thumb.
I do wish you could program more than three fingers. I used 2 of the slots for my right thumb (different angles) and 1 for my index fingers (so that it works with both hands). I honestly think it is heavily underrated and unless you don't care about security, I'm not sure how you can call it a gimmick (like the heart rate monitor, which IS a gimmick).
Two things...I can't wait for app developers to program apps that use it so that my App Lock runs off fingerprint instead of passcode or pattern (which is easily hacked). Secondly, Applke's version is better but Samsung's is better than nothing. I would give Apple an A (not an A-plus because of still existing degradation issues) and Samsung an A-.