I was in the same position. My battery life seems to maybe have improved now. If you read through the thread you can see the "host" of issues I have had with it. Charging up and then promptly rebooting as soon as I unplug it seems to have now fixed the battery life issue. I can't swear to that, but I think it has. I am around 77% battery life after a week of heavy use since I charged it last Monday. I've been reading probably on average 2 hours a day and also part of that time it was "stuck" on the drag to unlock wake "screen" since the n/power button got pushed when in my backpack coming back from a trip. That could have happened right when I packed it/loaded in my car 24hrs before I discovered it, or it could have happened as I was taking it out of my bag, not sure. At any rate, it was about 6-7% down from when I had loaded in the bag.
My first week of ownership I got 1 week of charge out of it (also was "needing charge" upon arrival). My 2nd week I got 3 days of heavy use out of it. The next charge I got about 5 days of light use out of it before it "went dead" from an 85% charge. Now I am on the most recent charge, and did the actual reboot after a full charge (previously I only rebooted several hours after the full charge, if that makes a difference) and going strong supposedly.
I did say battery was too low and needed to charge yesterday morning. However, my cat also knocked my nook ST 3ft off my night stand on to the hardwood floor immediately preceeding this message and it booted up immediately when I hit the power button when I took it down to breakfast with my younger son giving me an 81% power level reading. So I'll chalk that one up to the nook not liking shocks. Previous "battery too low, charge for 15 minute" messages really meant that, it would refuse to boot on until I plugged it in for awhile first.
The 14 days is for refunds, but there is a 1 year warranty if that helps. I've decided that even if mine has serious battery issues, I am just going to try an exchage at some point once I give this thing another few weeks for use/recharges. Hopefully, if this thing stays true to the battery meter this time (I did the once, but discharging very, very quickly that time) it should last me roughly a month of pretty decent use (I think it is rated at 2 months of like 30 minutes of reading a day I think, or maybe it is 60 minutes, 2hrs a day for 1 month seems pretty good to me).