No battery issues for me since the beginning and time on battery has improved with the updates. There are so many things that can cause excessive drain and heating up your battery. Like already mentioned, it could be a rogue app gone wild, video games especially if you have a lot of other things going on in the background, too many apps running in the background, etc. Check your battery usage statistics and your battery settings.
In addition, if you have a weak data or phone signal, your phone could be desperately searching for a decent signal which could cause excessive drain and heat. When I'm in areas with no signal, I turn on airplane mode because no amount of searching is going to find a decent signal.