Eh, I also find Concealment lackluster, mostly due to personally finding little value in out-of-combat defense. Threat reduction can be very useful, but it's situational and/or dependent on the archetype I'm playing. I suppose it differs according to people's play styles, and the content of the game is definitely a factor as well. Right now, if I'm discovered I just flee until I can stealth again or kill whichever mobs detected me; never been in a situation where I cannot flee and it's absolutely critical to remain undetected. I'm curious if the changes resulted in a noticeable increase in utilization by the playerbase?
I like the idea of certain archetypes getting additional benefits from pools when it makes sense thematically and mechanically. I'd also never turn down a little extra energy/negative energy resist, and I do find the endurance costs too high. Most of all, I wish I could figure out a use for Phase Shift. Such a cool concept, but just not useful for anything I'd want to do. If it was like Shadow Meld but with a shorter uptime, then I'd be sold on the whole pool.