Battery life on my smartphone has always been of academic interest to me, something to test and report but never actually having to worry about.
I've always driven to work (with my phone plugged in) and had a charger at my desk when I got there. The longest real test of stamina had been surviving some of the longer meetings that I attend (why are the longest meetings always the least interesting?)
Since arriving in New Zealand though, battery life has become an important consideration for me. Spending time learning about your new home is made much easier when you have access to a good suite of apps. The last thing I need is to be relying on my phone in a new country and have it die halfway through the day. No car and no office means no continual recharging.
The Galaxy Note 2 has really earned its stripes here. I've never had to worry whether it will last me to the end of the day - even making it last through a second day wouldn't trouble me unduly.
With a modern smartphone battery longevity comes at the cost of either reduced functionality or increased size.
I'll choose the latter every time.