my iPad 3 can nearly last all week (Monday-Thursday). my usage would be considered moderate i guess - but even that's all relative.
in the morning i download that day's issue of the newspaper and i read it while i eat cereal or i stream the news. then i put it in sleep mode most of the morning at work then whip it out at lunch time to DL a few podcasts, watch a few video podcasts, stream the news some more, etc. then it's in sleep mode most of the day. when i get home from work, depending on when my gf gets home i will use it to watch Mad Money and/or Fast Money while i'm cooking dinner. then later that evening i'll usually watch an episode of whatever show i am catching up on (tonight it's The Americans - that new show with Keri Russel on FX). sometimes it'll be a movie with the gf via AirPlay. then before bed i'll read the newspaper some more then put it in sleep mode. rinse and repeat Tuesday, Wednesday, Thursday - but on Thursday night i usually go out so i'm not using it that night. i can sometimes get it to stretch into Friday but if i stay in Thursday then i definitely need to charge it Thursday night. if i don't use it Thursday night then i start Friday with ~20% battery life and can usually squeeze out the rest of the day's usage if i go to work. what kills it is sometimes on Fridays i work from home and then i'm using it a lot and it'll be dead by lunch time (i'm up at 6am every day).
so yeah, the iPad 3 battery is impressive as is. i'll admit, the iPad 2 battery was even better. i could basically get it to last Monday-Saturday and then i'd have to charge it Saturday night before i go to sleep.
i had an iPad 4 briefly but didn't use it long enough to test out the long term battery life.
my girlfriend's iPad Mini lasts AN INSANE amount of time. i'm not even exaggerating. she has similar usage habits as me and can get it to last 1 1/2 weeks between charges. sheesh. that thing sips power like a hybrid sips gas lol