I've had mine for about 10 days now and compared to my EVO (Sprint) which strained to get 9 hours, my Maxx has been regularly pulling 30+ hours on a single charge. The best has been 36 hours with 30% remaining but I didn't want to stretch it any more than that because my next day at work was going to be a long one so I broke down and plugged in.
Typical usage for me is 4 or 5 short calls a day, dozens of texts, and periodic web browsing. I have 4G on, wifi only when needed (rarely as 4g is very strong where I live), GPS on, screen set to auto-brightness and I usually use short beeps for ringers and notifications.
Compared to what I was using prior, this is leaps and bounds forward for me.
I have FB running in the background all the time and it never uses more than 5% battery. I charge nightly and at the end of the day I am seeing 60% battery after 16 - 17 hours. 4G all day, Bluetooth all day, smart action to shut off Wifi during work hours. I keep GPS off unless I am using maps.
Emailed Tasker about doing the no motion like the Smart Actions. They said that leaving the motion sensor on all the time would take more battery so they shut it down when the screen goes off. I wonder if the OS use would go down if I turn that smart action off. I'm gonna give it a try.