I just did a comparison, light browsing on both side by side, screen at 50% brightness. Got 6:45 out of my almost 5 years old 2012 rMBP (which has an old battery), 4:13 out of my new rMBP. The new MBP is also only marginally faster, 10% for most CPU intensive applications I use. Needless to say, the new one, which doesn't even have USB ports or a Macsafe power plug, is going back.