I bought into the hype and even named my current character "Adapta-Billy," but the effects of Adaptability are totally lost on me. I've looked it up online and people have no solid evidence for the usefulness of most aspects of ADP, as well as Agility. It seems the only thing people are really certain about is that it increases the speed of healing... but I'm going from 40 ADP to 6 ADP and I'm not finding any noticeable difference. I can still heal in PVP and boss battles just fine. Shield raising speed? I don't really block much, and I highly doubt the difference (if there is any) is worth wasting the stat points for. And it raises fast enough as-is, anyway.
So I respecced and used the points that had me at 40 ADP to take me to some pretty high Endurance. I have shit tons of stamina now. You know what actually makes a difference? Having an extra weapon swing and the stamina to roll out of range in PVP. Stop wasting your time on ADP, people. Get that Endurance. 1 point per level is quite enough when you're level 125+.
Am I missing the big thing about ADP? It seems like a slightly less worthless Resistance (from Dark Souls 1), assuming of course that the rumors about it actually end up being true.