I have an N800 and my battery runs out pretty quick, but it is because of heavy use. I have Google Voice and I use my N800 for 90% of my phone calls(100% free calls). I am using Dialcentral and get free SMS messages all day long(Thank you Epage). I play music and run Gpodder for pocdcasts...when traveling I watch movies and/or stream video. Taking notes on Xournal and running Skype to see if friends are online....
Bottom line: I love my NIT. But all this constant heavy use really eats up the battery life. Not to worry...I have 3 batteries with an external charger. So I always have two charged batteries ready to go when one starts to get low. When on one of those long flights, I have enough battery power to watch 2 sometimes 3 movies on my NIT.
If you can get extra batteries and a cheap external charger, you can make all your iphone friends envious as you slap in the next battery on the go as they have to stop to charge up.