I read a lot of comic books. With some exceptions (Hellboy, Northlanders), most are superhero titles from the two major comics companies: Marvel and DC.
The superhero mold was stamped in 1938, with the first appearance of Superman. There have been highs and lows in popularity, but superheroes have largely dominated comics ever since. (As well as American culture in general. Superman alone has been featured in almost every medium popular in the last 75 years, from serial radio to over a dozen video games.) Despite this, or more likely because of it, people sometimes dismiss superhero titles as "cape books," or more commonly, "another f*cking cape book."
As comics struggle to find their footing in the new millennium, a lot of the blame for shrinking sales falls on the superhero books. Detractors see all superhero books as the same, churned out for fanboys already invested in the characters. The thinking goes that industry will never find new readers unless it expands into new genres. I'm all for trying new things, and again, I do read non-superhero comics (American Vampire, the recently completed Samurai's Blood), but I also believe that the reason the superhero genre has thrived for so long is because it's an incredibly flexible genre, able to be bent and stretched to suit almost any taste.
Not all genres are created the same. Some, like horror, focus on a single emotion. Others, like romance or mysteries, are hemmed in by conventions and audience expectations. But the superhero genre seems to contains an ever-expanding number of sub-genres. Just looking at stuff coming out currently, there's high adventure (Superman, The Amazing Spider-Man) and gritty crime stories (The Dark Knight, Punisher.) You've also got interpersonal drama (Fantastic Four, Birds of Prey) and epic story-telling (nearly every X-Man storyline since Days of Future Past). Then there's space opera (Green Lantern), teen angst (Ultimate Spiderman, Blue Beetle), comedy (Deadpool), and detective stories (Detective Comics, anything Ed Brubaker is writing). And around the edges, the superhero genre starts to crinkle up and examine its own assumptions (The Boys, Kick Ass 2, anything Warren Ellis is writing.)
This doesn't mean I love all "cape books" or agree with every decision the two major publishers have made in the past. I've written before about my disappointment in some of DC's most recent titles.* but I don't think the problem is that all superhero books are the same. Rather, I'm continuously amazed at how the superhero genre's ability to continuously evolve and reinvent itself over the past 75 years. And I think it will continue to grow--in one form or another--simply because it will never run out of stories worth telling.
*I still maintain that, if comics are going to survive, they've got to make a sustained effort to bring female readers back into the fold. However, my anger has subsided some since I wrote those two posts, mainly because DC is putting out some fantastic titles featuring women (Wonder Woman, Batwoman, and hopefully the upcoming World's Finest.)