You really can't use the battery status estimate as an indicator of actual battery life, especially in the first few cycles. It's just an estimate after all and it isn't perfect. It'll adjust and go up or down during use even when the power draw remains fairly constant.
To get an actual figure you'll have to drain the battery under the conditions of Apple's Wi-Fi test.
To do this, charge the laptop to 100% (leave it charging for at least 10-15 minutes after it says 100%). Unplug and use it only for browsing with Safari on Wi-Fi with a brightness no greater than 75% (12 clicks up from off). Don't open, use or switch to any other apps (or have them running in the background) except perhaps Text Edit or some other known low-power apps. You won't be able to do this in one sitting so close the laptop and "stop the clock" when it's asleep. The minimal power drain when asleep isn't significant. Keep track of the times it's in use such as when you start, stop and when it finally powers off. It may help to have an ad blocker installed in Safari.
Doing this should give you a figure of around 10 hours as claimed but I'd suggest 9 hours is acceptable. Less than 7-8 would be unacceptable and 5-6 would indicate a problem in my opinion, be it software (drivers) or hardware.
Make sure you test with adequate Wi-Fi signal strength as well.
