So my Lumia 900 (Cyan, fyi! heh ) is doing great.
I still have unlimited data, so yesterday off the battery I watched 30 min of netflix (On 4G), downloaded ~1 gig of music off of my Zune pass, and about 2 gigs of apps/games (installed a bunch of Nokia maps). These downloads were over WiFi. I texted a lot (subjective), talked on the phone for 47 minutes. And did about 3 dozen bing searches and a good 30 minutes worth of browsing (over 4G). As well as playing maybe 30 minutes of gaming and 60 minutes of other app use.
I took the phone off the charge are 7 am, when I put it back on the charger at 11:30pm I looked at the diag tool I was at 35%.
I have Push notification on for 2 emails accounts. I have 2 extra live tiles on the start screen that are not there by default.
I have WiFi on all the time. Bluetooth off.
Auto brightness, works good for me. Dark Theme.
Some notes on saving battery. Most of your battery usage (when not using the phone) comes from the quality of your cell reception! Low cell reception requires higher battery usage. I get excellent reception where I am at.
Also, things to turn off to save battery (that I have) and other various settings.
Turning off Key Press sound will save a tiny about of battery.
Lock screen time-out is at 30 secs.
Find my Phone is turned on, but the settings to work faster are turned off (save battery, saves a lot of battery if you have poor connection).
Phone update is not set to check over cellular.
Feedback does not send cellular data to send info! This might be critical!
If you are opted in the bing searches, pictures, etc etc to send the info to Microsoft, this could be wasting a lot of battery!