I'm very sad to inform you the battery - at least for the 2015 model - stinks. Coming from a 2015 MBA 13" it's incredible how much one can get used to day long battery life.
I don't do anything special really with my MBr. My usage profile hasn't been changed since years.
I have open:
Always: Firefox with 5-10 tabs, Telegram, iMessage, Sublime Text, MAMP Pro, Little Snitch and 1Password, Wifi
Sometimes: Excel, Whatsapp, Chrome with 1-2 tabs
Battery life dropped from at least 7 full hours on the MBA, to about 3 on the MBr.
It will be my only reason to switch to a new - soon to be released - MBPr 13 (or whatever it will be called).
But again, for the rest this is one fantastic piece of kit.
Wow..that is pretty poor battery.
I have Safari with 5-6 tabs open, Word, Excel
Chrome 2-3 tabs and check FB and Salesforce, as well as use for all my email.
Stream some music on Spotify. Brightness is around 75%. I'll even watch some video on Amazon as well.
I am around 5-6 if I watch the video, 6-7 without it. So a lot better than you are seeing.
With a new MBPr that they are talking about, I would be shocked if you can do better, given the higher specs.
All that said, the MBA blows this away, but that's the price you pay for Retina I guess. MBA was spectacular with battery life 9-11 hours under same conditions.
I'm happy with my purchase as it stands. You tell me I can get close to 7 hours of battery under these conditions with a machine like this and that's fine for me.
ONE NOTE - I removed Chrome over the weekend as a test. WOW..what a HUGE difference in battery. Getting rid of Chrome alone, I was using my MBr m5 constantly yesterday. I was also outside for some of that time, so my brightness was 100%.
I got 7:45 and still had 10% left when I shut down.
I had Chrome only because I needed to use a Browser extension only Chrome has for gmail, but decided to forgo that. If this keeps up, I am going to keep Chrome off my machine if it means getting close to an hour more in battery.