Just picked up my copy of Dungeon Crawl Classics. Although I did not find it at a booth at Origins, as I had hoped for (Origins was pretty much OSR deprived, I only found one booth with much OSR stuff), my local game store got it in the next week. My reaction is a bit bittersweet. I think it is a perfectly playable game, many people will have a great hoot with one-offs using this system. However it incorporates a large dose of random lethality that will inhibit long term character development, and leave many characters, not retired but so gimped up as to be no fun to play. The good is that it is a large book at a reasonable price, it is published under the open gaming license (yay!!! that's a big plus in my book) and play could be a hoot. The bad limited character classes and few options to make them unique (although this is typical OSR), your character could explode, randomness instead of game balance (more on this below). The funky, using different size dice instead of changing target numbers, arcane check charts for casting spells. Both these ideas are definitely out-of-box thinking, but look like they'll work.
Thing that worries me the most is the randomness. Randomness in itself is not bad. However random tables with small but finite catastrophic occurrences tend to tilt out of balance quickly (subject to both the long tail and black swan events for you economic statistic junkies). Those players who always role well will prosper under this system, folk like with often sub-average luck are screwed.