I'm using Chrome 35.0.1916.153 m on Windows, and, um, there's something wrong — there's nothing wrong with the web fonts! Apart from the Merriweather Ultra-Bold that's titling De Beneficiis, that is (and a quick check at Google shows that that same font is rough in the bold weight as well). Everything else is clean and well-aliased, and that's never been the case before.
I'll just put a little note on my site instructing users of Chrome on Windows to do that :)
It has been YEARS of putting up with the horrible Google font rendering in Google's browser on Windows, all the while IE and Firefox render them perfectly.
or run the new 64-bit chrome. I could never get the DirectWrite flag to work for me. Finally I got things working via registry changes, but I undid them and installed the new 64-bit beta and it's been amazing.
The Windows font rendering system tries to aggressively fit typefaces into the pixel grid. This is a throwback to low PPI displays from back in day.
Linux's fontconfig allows for all sorts of configuration. Ubuntu, by default, probably has the nicest config. Otherwise, I personally turn off all hinting but leave subpixel rendering on. Brings it closer to what OSX does.
Personally, the best font rendering I've ever seen is on a high PPI Android phone. Most pages that are more than 2-3 paragraphs I forward to my phone for reading, since my desktop displays aren't that great.
What you're seeing is that Chrome is using the (terrible) old Windows GDI ClearType font rendering, whereas Firefox is using the (newer, less terrible) DirectWrite font rendering. This can be enabled in Chrome by visiting chrome://flags . Specifically, what you're mostly seeing here is that ClearType does not antialias in the Y dimension, which is why you see stairstepping. (Firefox will also use GDI font rendering if it is not using Direct2D acceleration, IIRC.)
Of course, a lot of people have complained that DirectWrite rendering is "fuzzy", so to each their own I guess.
I've been starting to use webfonts and this issue has been very annoying for me (as a Linux user, where pretty much all fonts look good).