I am 33 and I look back on my 20's as a total void of utter bullshit fuck. The only thing I achieved was a few addictions, some scars and health problems and a racking up of debt. My 30's, on the other hand, have been pretty good so far having studied to near completion, working full-time and owning my own shit. I've decided to simply write off my 20's as a traumatic learning experience.
Now that I am older with less headhair and greying beard hair, I've freed myself from suffering considerably, though am still a sucker for self-punishment. I would rally hate to have to live my 20's again; I was angry, aggressive and highly antisocial. I'm basically much less angry :D