Ok so here my two cents as an engineer currently building a Windows 8 game. I've been using Windows 8 since DP4. I.e. Developer Preview 4. Currently I'm using DP6, which is the latest build since the Consumer Preview (CP) was released. I have gotten used to the Metro interface and use it as an app search and launchpad. Basically I see the whole Windows 8 thing as basically a faster, cleaner, sparklier Windows 7 with a revised Start Menu. It's clear some optimizations have been under the hood to make the OS load faster, run faster, and in generally be more efficient.
As far as the Metro interface goes, it's fine. I use it with both my touchscreen monitor and mouse and keyboard. It doesn't make my day to day job any easier or harder, it's just different. Also, keep in mind that as a primarily back-end dev, I need to use all of the more advanced features of Windows and so far haven't found my experience to be any worse than Win 7. The only bad thing right now is the massive buggy mess that is Visual Studio 11.
Win 8 is basically Win 7 with bells on. You can pin Non-Metro apps to the start screen and the app/settings search is fast. I use the start screen merely through my keyboard. Hit Windows key, start typing app-name, hit enter. That's it. As far as Metro apps go, I don't really use any except the game I'm working on,,, which rocks.. ;)