So far in my experience of almost 2 months and 3 lumia 800s, i've come to the conclusion that the call ending issue is related to post call notifications on pre-paid sims (i have the same myself). And the work around for it, till the time it takes MS to come up with a fix, is to disable the same. Did this about a week back and havent had the issue since then. I would suggest every one to get in touch with their service proviers on the same.
Just a heads up, Vodafone subscribers in India can do this by messaging NPCN to 111. You receive a confirmation message and the service gets deactivated within 48 hours.
And regarding other issues like battery, etc. I really dont know what people are complaining about. With hourly checks for mails and a couple of live tiles and ocassional gaming, my phone generally gives me about 30 hours in a single charge. Dont know about others but thats pretty much satisfactory for me. And this is when my battery shows a charge capacity of around 1350 mAh.
Overall its a great phone and does about everything you can expect from a smartphone. 
The fact that you can get 'about 30 hrs' doing all that stuff on your phone, and I can't even get mine to last 18hrs doing *Nothing* at all, would suggest a big problem with some handsets.
Overall, it is anything BUT a 'great' phone! Can't end my calls, phone crashes, battery life is terrible. That's not great in my book
I'm glad your happy with your purchase, I hope Nokia deal with the customers who are experiencing these problems, quickly and effectively.
Until now, like every one else , i used to believe that the issue is due to the "POST call notification"
BUT I FACED THE SAME ISSUE WITH A RECIEVEED CALL
In fact i was at the NOKIA CARE CENTRE ITSELF,
I was there to recieve my lumia 710!
NOKIA NEEDS TO RETHINK..,is it just the Post call notification that causes this issue? or something else.. EVEN INCOMINGS ARE EFFECTED!
