Just like your favorite laptop... A battery may last a year, and another can still be happy after 4... it's often a bit of a lottery.
I'd expect a couple of hundred cycles if treated well.
The "battery life" is displayed in the batery info page and it's reported in %, i.e. how much of the original capacity it still has. It's not "black or white",it will just gradually decrease with age/cycles. When it's not enough for you anymore will be your own call.