I switched from the rezound (which I loved) to the maxx due to battery issues. I use my phone a lot being a business owner. My rezound would last about 4 hours before I needed to charge and that did not work for me.
I am very pleased with the maxx! I am easily getting 18 hours with pretty heavy use. And I really like what ICS has done for the phone and blur.
I wanted to wait a good week before posting this and really get to know the phone. This is really a great device! I can certainly see myself keeping this phone for a long time.