I absolutely love the physical home button, and only "like" the capacitive buttons. I find that sometimes when you go to hold the phone sideways/landscape, you have to hold the phone on the rim and not let your finger/thumb touch one of the capacitive buttons. Not a huge deal, but it does mess me up every once in a while ... and when you hand your phone to someone else to take a pic of you and your wife and/or kids - and that person is not used to those buttons being there - what almost always happens is they look at you and say "uh oh ... I think I messed something up" ... meaning, they probably hit the "back" button and the camera turned off LOL.
That said, the physical fingerprint scanner home button is awesome, and I wouldn't trade it at all. I also think that while those physical buttons take up some room that might have possibly been able to be more screen size/space, or make the phone shorter by eliminating that space, it's a good trade-off for me. I find the S6 to be perfect size (it's just a TINY bit taller than my S4) ... and the screen size is more than adequate for me.
As for cameras, I find that my S4 took pictures that were plenty good enough for me - at least quality wise. The big improvement I would like to see is good optical zoom. That's the biggest hurdle I think smartphones have to overcome, since (from the little I know) that would take a "thicker" lens set or arrangement to get a stronger true optical zoom ... and then we end up with even thicker phone bumps on the back of our phones.
In the end, I will admit that while I love the thinness of the S6, and the quality of the camera, I would have probably been happier with a slightly lesser camera and a thicker phone (with bigger battery) so that the phone was perfectly flat on the back. To ME, that would have been the best thing ever. I love running phones w/out cases, and am "afraid" to run my S6 w/out a case strictly because of the huge camera bump on the back.
The fact that the back of the phone is glass doesn't help that either, but I get the reason - wireless charging. It's just w/ the glass back, and the camera bump, I feel like the phone is going to be too easily knocked around and broken. If it would at least lay flat (like my iPhone 4S did, with a glass back), I would feel MUCH more at ease w/ running the phone w/out a case. I did that for a couple of years and never had an issue with a glass back.