Good to read your thoughts!
I didn't think it would win you over, but to be honest, the reasons youve quoted for not enjoying the device are not what I would have thought you'd say haha.
I personally love the feel of the back. Much prefer it to a metal back which is cold to touch and very slippy (iPhone 6, looking at you), but I understand it isn't for everyone!
I completely agree with the majority of what you're saying. Battery life is middling. I've used my phone sporadically today - not much at all. It got taken off charge at 7am and right now it's on 54%. Not bad at all, but I've not done much with the device.
The heat of the phone - yep, definite issue. I find it mostly happens when using Google apps. Chrome for instance, makes it boiling. I've tried other browsers and don't like them.
I know I've said it before, but I am hopeful Marshmallow fixes some of these issues.
For my needs, it's perfect. But I wholeheartedly agree with you in saying that if they replaced the chip and made this thing with slightly more premium materials, they'd be on to an absolute winner.