It's conceivable that, if we built rockets fast enough, a human explorer could travel to this planet and reach it within his life-time. The universe outside the rocket (which obviously includes his homeplanet as well as Kepler 22-b) would have aged more than 600 years in the meantime though.
I dunno about this planet though. It could be made of anything (gas, solid ground etc.) and it could be hotter than hell or too cold for liquid water to be present, depending on the atmosphere. Even if conditions are "just right," it may not even have life in any form anyway. Even if this is the most likely candidate to support advanced life, for all we know it may still have very slim chances of doing so.
Can't wait till JWST takes a closer look at it, though =D