It's well known that Apple uses software to drive hardware sales (as opposed to a company like Microsoft which is the exact opposite), but to give away the OS for free took a lot of people by surprise.
Anybody tried it out? What are the new features/applications which help from a development perspective? Is it a real time update (or does it download the installer?) In case I choose to upgrade, any recommendations on how to go about it? (I got burnt once when I opted for upgrading Ubuntu instead of clean install)