It can be a gamble, yeah. But plenty of people on here swear non-Samsung/cheap (as opposed to more expensive ones from reliable companies like Mugen, etc) batteries are fine from lots of manufacturers & they've had good experiences with them, however, if you look through Accessories/elsewhere, you see plenty of people who haven't had good experiences with them.
If you want a battery to work exactly as it should, be at or very very close to the rated capacity printed on the outside, and to last you a reasonable amount of time/give you plenty of use guaranteed (important word), then buy Samsung branded batteries. You know the quality of manufacture is consistent/of a high standard, and if you somehow get one that isn't, it's easy to get a replacement or your money back (and cases like this are rare).
If it's important enough to cause you grief if it's lost, back it up. No excuses
Trolling for thanks is lame
Does Samsung's auto-brightness implementation crap drive you to self-harm ? A solution !
Most retarded thread on XDA in 2013