It's a fantastic power. Definitely not a glorified rest. Especially for Ice/Cold where you don;t have a self-heal. Taking to much damage? Hibernate to full. Accidently aggroed way to much, and now you got 2 bosses and half the mob focused on you? Hibernate till your team takes aggro.
Bind it to an easy to reach key so you can press it immediately.
Hmm. Maybe I'll have to transfer a version over to test and play with for a bit. However, I guess a better way to put the question would be: is having that panic button more useful than building to good defenses? With the build I'm working on with Scorpion Shield, I have around 36% Defense to Smashing and Lethal, softcapped (or very close to it) Energy Defense, ~30% Negative Energy Defense and, I think, 33-34% Defense to Ranged. This build is also getting pretty good global recharge. With using the build that has Hibernate, the best numbers I seem to get is 32-33% Ranged Defense and ~30% Energy/Negative Energy Defense. I mean, it does sound good in place of a self-heal, but I've played this whole time with only inspirations to heal me just fine.
Ugh, sometimes I make this min/maxing stuff more trouble than it needs to be. Oh well, at least I have fun making builds and working the numbers. 
I have never used hibernate, but I am a huge fan of scorpion shield. Like you said it makes it so much easier building defense and think it is the best power a corruptor can take from his epics or patron based powers, i use it on all of my corruptors.
I've been working on builds for my Ice/Cold Corruptor, who just reached 47, and every build uses the Leviathan Mastery so far because, conceptually, its the closest to ice I can get. In those builds, I include Hibernate because I think it might be useful, but I've never actually used it in play. However, after playing around a bit more, I found Scorpion Shield so much more useful for the goal of building defense and recharge and its also only one power pick. I can work it in conceptually, although I'd prefer something cold-based... So really, what I want to know is how useful other players have found Hibernate on a Corruptor? Is it really anything more than a glorified Rest for the squishy ATs?