Lack of a removable battery is a deal breaker for me.
My wife and I actually swap batteries in our S3's at times when we are out, one of us needs juice badly, and charging is either not convenient or possible. That option is now off the table, as would be a spare battery. I also replace the batteries in our phones after about a year. By then, you can get a high-quality higher-capacity replacement for very little since the phone is no longer the current model. That capability is also now off the table.
And what replaces it? A fingerprint magnet slick back that can shatter. Yeah, like I want even more glass on my phone. And for that I give up a replaceable battery and SD card expansion. Not even close to a fair trade.
Frankly, I would be upset about the SD card as well if my S3 didn't eat them. Way to condition me not to rely on it Samsung. Nice planning.
I know everyone is falling over themselves in love with this thing, but I just don't see it. It appears to be the "Apple-ization" of Samsung - almost completely about the packaging at the expense of functionality. Seriously, plastic grips well and is rugged. How good is that metal frame going to look in six months after some bumps and drops? Get back to me on that.
Yes, the F1.9 rear camera is nice, as is the built-in wireless charging. Great job on that Samsung. You are only behind Palm with built-in wireless charging by about 6 years...and they managed to have a removable back on those devices.
No, it's not going to do it for me. I waited for the official announcement to be sure, but now that it is clear that the S6 is mostly about packaging at the expense of functionality and is nowhere near bloatware free, I'll be picking up a Note 4 to replace my aging S3.
Of course, I am almost certainly in the minority. Shiny fancy things will resonate with most Americans. I am sure they will sell like hotcakes.