Ah good old Robster3 and his "I had a galaxy S5 and it gave me issues so those apply to everyone else as well", routine.
The camera is great. Not perfect, but great. There's better low light cameras out there, including both current iPhones by a whisker, but they're pretty average too in low light.
http://www.dxomark.com/Mobiles/Samsung-Galaxy-S5-overview-Joint-leader-in-DxOMark-Mobile-rankings
I don't have any issues with the flap, sure, no flap would be better, but if you find it hard to use, you have dexterity issues, or no fingernails. I open mine nightly to charge my phone, any inconvenience of a flap is countered by having to only charge my phone once nightly , it's a good trade off.
The battery life is great, it even charges faster than an iPhone 5S, but robster will tell you the 5S charges twice as quick, lol.
Basically, don't listen to Robster if you want objective opinions, he just love bagging anything Samsung, doesn't do anyone any favors really.