[Galaxy S6 Q&A, Help & Troubleshooting] jmtast:
I will add my experience to the one that said not so good things about the phone.

1. Do you still have the out of RAM problem?

This problem is still there. I think that whoever says it's gone, does not know how it shows up. It's not about how much RAM you have free or not, or how much it lags on daily use within an app, but how many apps it can hold open at the same time. This is clear when you open some apps and "exit" them using the home button instead of the back button. You can easily see that if you open a webpage in Chrome, open a couple other apps (always using the home button, not exiting with the back button) that when you go back to Chrome, the website reloads from scratch, meaning that the RAM manager has killed the app and has to fetch everything again. So no, the RAM problem is far from solved. Hope they fix it in future updates, but I wouldn't bet on it.

2. How is your battery life?

I feel this aspect is really flimsy and blame it a lot on Google and it's Play Services. It can't be that while rarely installing or changing apps or they way I use the phone, my battery life is so irregular. Some weeks it's good, some is downright bad, then back to normal, I don't know. I suspect that the only thing that can change and affect this without me noticing apart from the battery life, is the Google Play Services and their shadowy background updates. The first weeks with the phone I was seeing like around 4hs or more SoT, and now 3 months later, I see from 2 and a half to 3. Had the same wobbly behavior with my previous phone (OPO), sometimes great SoT, sometimes just bad.

3. Is your phone (with Touchwiz) still snappy or did it become slow?

I would say that it might have changed but not substantially. It's by no means slow or unacceptably laggy. It's clearly no Nexus, but if you already know what to expect, I'd say it's good. In a scale from 1 to 5, being 1 painfully slow and 5 Nexus like, I'd give it something between 3.5 and 4. It's ok but it could be better.

4. Did you have problems with broken backs?

Not at all. The phone is not that heavy LOL. Now seriously, if there's something that I, as a Samsung hater between the S3 and S5 era, can congratulate Samsung for, is the build quality and materials. Top notch all the way. Solid and precisely crafted.

5. Does your phone run hot?

I notice it gets hot sometimes on the top right frame (above the power button), but you notice it just if you go and touch that part, the whole phone does not seem to have a problem with temperature. Didn't try to push it to have one, though.

6. Would you still buy it now?

I've been looking for a replacement just because I miss stock Android and the Nexus brand, but I am really not convinced by any of the Nexus since the OG Nexus 6. The Nexus 6 is just gigantic, not for me (the OPO was big for me, that's why I ended up with the S6 and love the size, it's perfect. Although I'd prefer it to be thicker to even out the camera bump and make space for a bigger battery. I don't win anything by having a phone this thin compared to this thin + 1mm of the camera bump, I think that decision was just dumb). The Nexus 6p is way better but still big (it's bigger than the OPO) and there are way too many reports for me to jump on it yet. The Nexus 5x does not convince me because I feel Google made it worse on purpose so that people preferred the 6p over the 5x, not just for the price. I would have loved to have a 5x with the specs and benefits (for example, the extra cable or the higher framerate filming due to the extra power of the processor).

Would you still buy a S6/S6 Edge today?

With all that said, I think that today as they said before, with the prices dropping, it's a great option. Even more if you care a bit about the camera, which is awesome. If it only had a bit better battery life, I would not think about replacing it anytime soon, but that and having stock Android always makes me think about other devices. Maybe I'll root and put a custom ROM to it, a stock based one, but with better battery life and less bloat. OH, SPEAKING OF BLOAT: it comes bundled in with some Cheetah Mobile software that cannot be uninstalled or disabled. That drives me freaking nuts and I hate both Samsung and Cheetah Mobile for that. Like, bad. For reference: https://plus.google.com/u/0/+JuanManuelTastzian/posts/88sYktUP7oq

Hope this helps and sorry if the post is too long.