I don't think height has much to do with it. The only person I know outside of this forum who has a 6+ is plenty tall with regular sized hands and he hates his. He says it's great at home for watching video. Problem is, that's very little of his day because he has a life. It's not comfortable in the pockets of his pants (no, not skinny jeans), it falls out of the pockets of things like hoodies, it's too tall for dress shirt pockets, etc. He finds himself having to carry it in his hand most of the time, which is a nuisance.
His experience was a key factor for me in getting the 6 instead. I really wanted the OIS and thought I'd be OK with the portability issue. (I use the 5 two handed, so that's not an issue, and I'm female, so a purse is fine outside the house.) But comparing the pics here and from various reviews using OIS and without it, there's little to no difference--it's not as dramatic as having stabilization on a giant SLR lens, that's for sure. Handling the 6+ in the store made my hands hurt (even the 6 does to some extent, in spite of my long fingers.) It felt almost top heavy due to the height. And when I started paying attention to how I actually USE my phone on a daily basis, I realized I'd be in the same boat as my friend...having this nuisance that I resented having to carry everywhere in my hand because it didn't fit well in my pockets.
Everyone's use case is different, obviously, and the 6+ is going to be the best choice for some. But in the end it wasn't the best choice for me, and I'm glad I found that out before buying one. If I need a bigger screen, well, that's why I have an iPad, or a 17" laptop, or the giant TV in the living room. And if I need a good low light camera, I'll just have to haul along a real one, because the images I've seen from the 6+ just don't compare.