Icy - The battery in the 920 is MUCH bigger than the iPhone. I've had the same battery issues as you with my iPhone5, but I really have no choice but to deal with it.
The Lumia is a different story. The iPhone battery is too small, but the Lumia has a great battery - two different issues. I honestly believe there are some bugs in the mail sync process (specifically for gmail) as well as some apps that aren't fully compatible (not yet updated) with windows Phone 8 on the Lumia. I honestly expect these to be resolved quickly.
I don't have any issues, but I think it's because I don't use gmail, nor Nokia drive. I use Nokia music a LOT, but I get OUTSTANDING battery life. It seems the issues are related to some apps getting caught in a loop and just burning up. Again, I think this will be fixed. The iPhone however, the battery is just too damned small ... it will be fixed with the iPhone 5S hopefully and the 5 will be forgotten as an unfortunate mistake.