The Lord of Time realizes that time has been shattered (to put it mildly) and figures out that the rise of the Anti-Monitor is the pivotal moment in DC History he must change. He zips back to 1984 and stops the Crisis before it begins. Everything that happened since then is wiped clean, and characters act as they appeared back then (heroic), to meet new challenges and adventures in a multiverse uncluttered by the last 30 years of continuity. Batman is no longer a brooding sociopath, Superman is in a love triangle with Lois and Lana, and the Justice League of America is a bunch of cool dudes hanging out in a satellite.
You'll guess that I'm an older reader who despises nu52 with the passion of a thousand suns; as a matter of fact, I haven't been too happy with most of DC's decisions since Crisis (a bloated, unnecessary yarn that in the end doesn't make much sense). That's my problem, of course; I'm suggesting the above simply out of curiosity whether other readers felt the same, and as well to ask: what era of DC history 'works' for you guys?