For the record, especially for users running newer kernels (I suppose starting from 3.3 and above), AMD's drivers break a lot to the point you have to use updated drivers from AMD's own site and not from repositories, if you still want to run the newer kernel AND not break the current AMD driver in your machine. And by "breaking" I'm saying that DKMS has troubles building the driver modules for these newer kernels (and I've been having this kind of problem a lot).
Sure, this is no problem if you stick to the stock kernels supplied by Ubuntu's repositories, but in the long run, this will pose a problem especially as kernel versions get one step higher.
For me, not only the OSS drivers aren't fast enough (though I never bothered to run anything past desktop composition and effects), they cause increased operating temperatures for the GPU (+ ~10°C in my case) and I can't accept that running in my system.
But then again, I'm neither against nor am I for any kind of petition. Jokingly speaking, we should already be able to know that this is one of the hints a hardware maker is giving users to start upgrading their hardware (much to our own chagrin and against our protest of not wanting to). While they might hear it's still up to them to decide.