So basically, you're getting an Android phone, minus the 700,000 Apps? Thanks, but no thanks.
The whole idea of using HTML, CCS, and JavaScript as the back end technology for a low-end smartphone is nuts. Even the best HTML rendering engines are CPU and memory hogs. CSS was never designed for and is nearly impossible to hardware accelerate, and JavaScript is notoriously difficult to optimize and even the best VMs like V8 run orders of magnitude slower then Native code, while the VM itself takes up a massive amount of memory.
Mozilla should focus on building a competitive browser. At the end of the day, I want a responsive fast phone, like the iPhone or Galaxy S3, not some dog slow HTML5 monstrosity.
This isn't a new competitor to iPhones etc. It's a platform for inventing the next set of web APIs. You're getting a phone that encourages apps to be web apps instead of locked in to one platform. Users can get any phone they want, with any OS they want. Web apps will not be crippled. They can access the phone functions, the camera, location etc. Since web apps are now first-class apps, developers can write one app that runs on all phone platforms. Users still get to pick a "native" app ecosystem they like, but they will also get first-class web apps that work on every phone.
Using an Android kernel also allows Mozilla to leverage Google's Linux work and get hardware support "for free" from hardware vendors who won't bother writing drivers for non-Android Linux.