The software has all the functionality you need to record, edit, and mix your music. If you don't play an instrument or sing, there's a built in synthesizer loaded with loads of software instruments so that you can compose directly inside the software, or connect an external hardware controller to trigger notes. Once you're done laying down your tracks, there's a suite of effects, sound processors, and a couple of basic plug-ins to get you started. In the event that you need more plugins, you've got access to loads through the app's marketplace.
It's hard to see what the catch is. Obviously, this software is going to have lots of functionality limitations compared to the full Pro Tools suite. It's possible that Avid's hoping to make money off the plugin marketplace, where people will go to stock up on better editing powers. More likely than not, First is a play at roping in people when they're just starting out. There are plenty of free options for beginners out there these days, and if Pro Tools doesn't plant itself in people's minds early on, it risks losing paying customers later.
Either way, it's exciting that everyone will have access to some Pro Tools. Right now you cansign up for updates for when Pro Tools First will be available. I'm excited to see what it can do.[Avid]