Marv made an interesting comparison over on the Goodman Games boards. To me, Dungeon Crawl Classics is like a Super OD&D (in the tradition of Super Mario Brothers games). Indeed, it has many similarities to the three little brown books of the original game, yet it makes thewy additions and expansions to that base as well. The first volume of that game alone shares basic assumptions about the social scale of experience levels, the power of classes, the protected niches of characters, the nature of magic.
Take magic, for example. Via Chainmail, the magic system in the original game is highly unpredictable, where magic-users can cast a spell only to find their spell miscast without benefit (and lost), cast successfully (and retained for future use) or caught somewhere in between, in limbo until the next turn. DCC takes this basic principle and adds much more detail, so that miscast spells might also transform the caster into a hideous creature, or successful sorcery might prove unexpectedly powerful. Add in supernatural patrons and character-specific spell manifestations and you have a magic system that is built from the same basic foundation as OD&D, yet with much more muscle to it.
Similarly, the progression of power for fighting-men is modelled directly on OD&D. While later "advanced" editions of the game weakened the fighter, introducing the "linear fighter, quadratic wizard" quandry, it is important to remember that this problem is entirely foreign to the original three little booklets. A ninth level fighting-man was simply nine times more powerful than when he first started out (similarly so for magic-users). He fought as nine men, with nine attacks (each the strength of one man's strike). While his "advanced" cousing, the fighter of AD&D was reduced to two or three attacks a round, the DCC warrior returns to native soil in a unique way, making three attacks, each strike the strength of three men (for identical output to the OD&D fighting-man, but with less dicing). Add in critical hit charts, fumbles and mighty deeds, and again you have a robust and powerful addition to the original game.
Even the social scale of characters in DCC is reminiscent of the original game, where a first level warrior is no mere soldier. Roughly speaking, a first level character is already the hero of the townships, an unlikely local that rose to unexpected prominence for his deeds. His tales will be told in the few villages of the valley for several generations. A level two character is the celebrity of a major city, well known by all but the unsophisticated. By third level, an adventurer has already rose to the prestige of a conqueror-king or slayer, whose legend will endure. This is far removed from the scale of power in later games, but is actually perfectly in line with the concepts found in OD&D.
More comparisons can, of course, be drawn with the other volumes, but this is just what comes to mind while paging through Men & Magic. I am curious how this plays out over longterm play, but I suspect the pace and style of DCC would be very reminiscent of the original three little books. Of course, it was always a design goal of DCC, it seems, to start at 1974, but only go backwards from there, instead of forward into the future.