Edit 2: Also considering that, once upon a time, I was the Program Manager who would've owned implementation of this misfeature, I feel entitled to complain.
I've been using it for the last 5 months or so. Honestly, it's 15 labels at the top, all of which I know the positioning of. They could be cryptic/obscure symbols from The 5th Element, and I'd still know what each one does based on their position. Yea, it takes a couple more seconds to parse the menus the first time you look at it, but after a while you memorize what they are anyway. If menu readability is the worst thing people can find about VS2012, then I'd say they did an OK job with it.
I don't think most people are honestly saying "oh dear, how will I ever find the Debug menu".
They're objecting to an obviously annoying move with no clear rationale. The VS beta had an entirely different set of text in all caps. The fact that they had to hunt around capitalizing stuff in order to "Metro-ize" it just shows its mainly a political move. (Office 2013 has also gone the route of randomly capitalizing things; there is apparently no motivating rationale for which parts of the UI on a desktop app deserve caps.)
Users are rightly annoyed that Microsoft's making these silly changes, and because they're so visible, of course there will be a lot of vocal feedback.
A more cynical person might even think this was by design: Make one really prominent annoying feature, and drown out concerns on anything else.
I've been using 2012 for 3 months and honestly I'm starting to like the all caps. As the main menu bar it helps to disassociate it with the rest of the however many toolbars you have open. But really, it's one very small part of a massive IDE.
This is exactly how I run VS 2012. The VSCommands addon[1][2], allows auto-hide of the main menu, fixing case, and some other nifty UI fixes. I expect the author will do quite well just by fixing the stuff people are pissed off about.
I don't believe it has been released for 2012 yet, but I am pretty sure it will be (I can ask Matt tomorrow at work, but I can't see why he wouldn't as I don't believe it would require any changes, just updating the manifest to say it supports 2012).
I'm far more annoyed by the new icons than I am by the CAPS MENUS. They may actually force me to finally learn their key bindings after all these years...
Funny how it seems the only people in the comments here who seem to be complaining about the all caps menu(which can be turned off with a registry setting) are people who don't appear to be using VS on a regular basis, if at all.
Edit: there are actually studies on this. See, for example, this: http://en.wikipedia.org/wiki/All_caps#Readability
Edit 2: Also considering that, once upon a time, I was the Program Manager who would've owned implementation of this misfeature, I feel entitled to complain.