Since purchase back in December I've been getting about a week between charges, with notifications on and 2-3 hours of GPS use each week.
Over the past few weeks, that's dropped to 24 hours! From the forum, that appears to be about the time that 4.0 came out (how does one get a notification before/during an upgrade, or a choice of whether to apply it or not?).
Any solutions? I've already turned off notifications, auto-on display, and everything else I can think of to improve battery life.