I think it will be fine for the avarge consumer user. Im also sure there must be power effeciency stuff made to both hardware and OS from n810. for the IT specialist there might be an expension battery pack from Nokia or Mugen.

I have the Mugen 3600mha battery for my n810 and use it for 3 days while never turning it to flight mode (online all day and night, home and at work).