Take a gander at this 20-Point Letter of Protest Regarding the New 4th Edition of Dungeons & Dragons (from a Gnome and a Half-Orc). Beneath all of the silliness, there's actually some insightful commentary about both D&D and the new edition. Some of them are points I've made myself or to which I am sympathetic.
Suffusing them all, though, is the most important point of all: the loss of an entire "culture" of gaming. Odds are that even younger gamers, who never played 1e or even 2e, let alone OD&D, get most of the jokes in that list of 20 points. That's because there was a common culture of players. We all spoke the same language, if you will, and shared in common experiences, including bafflement at the 10 x 10 room with an orc guarding a chest. That culture has its roots in the 70s and has been constantly under attack by designers and gamers alike, who want to "update" D&D in various ways, without regard for which fraying thread of the tapestry might be the one that unravels the whole thing. I'm not saying that 4e will be a D&D "culture killer" by itself, but there are many things in its design that trouble me as someone who places great value in the traditions and heritage of this hobby. Time will tell, I suppose, if my fears are misplaced or not.
Tip of the coif to Jason Barker for the link.