I necro'd myself just to reply to this thread.
First, to the OP: your question has been well-answered by waderockett. Even a bump from Penny Arcade (worth pure gold in marketing dollars) won't ever make 13th Age bigger than Next, and they are cool with that. I think waderockett said in a different forum: all boats rise together. If Next is popular, that will open the market to other new ideas as well. (And, yes: probably the vast majority of casual gamers have never heard of either.)
Dragonblade: I liked your summary a lot. Personally, I find a lot of the mechanics to be something I'd call "4.5." The classes, character sheet, power selection, leveling process - all of them are strongly reminiscent of 4.0. A lot of monster actions/powers are as well. It's not really fair to label 13th Age that way as a whole, though: it really does a wonderful job of tying in a lot of the RP into the mechanics as well. And they have a ton of ideas that you'll find in D&D Next (I'm sure they were independently created). They are just good ideas for D&D in general. This is a great way to put it:
13th Age is amazing, and I love how it appears right now that I could run either Next or 13th Age as my base, and steal lots of bits from the other. For example, the entire magic item doc in the Next playtest can pretty much be dropped as is into a 13th Age game. Likewise, the advantage mechanic from Next is a perfect fit for 13th Age.
Conversely, I can go the other way and import Backgrounds, Fail Forward, the Escalation Die, and the mook rules from 13th Age into Next. I love it!
I have done exactly the same and plan to do exactly the same.

13th Age's strongest selling point to me is the modularity of the best ideas, and its accessibility to D&D 4.0/5.0.
Light Knight: I agree that if you like heavy simulation, this isn't your thing. It's even more abstracted than 4.0, and while I wouldn't say it was "more for roleplaying mechanics" similar to a game like Vampire might be, it's definitely headed in a direction away from what you liked. Sadly, I don't know of any way to get your hands on any of the "crunch" other than pre-ordering, either. But they say they'll be releasing their game under the OGL, with its own SRDs, so eventually this should be available. I will say that you do get a lot from the book itself, though, including lots of the designers' notes about
why something was done a certain way, and how you can change it if you don't like it.
Personally, I'm really digging the game myself, and it's already changed how I will play D&D games going forward, so for me it was worth the pre-order. I just wish there were more places online discussing the game.