Anyone can join the OS X Beta Program and download OS X Yosemite 10.10 Developer Preview. The truth is that the current Developer Preview build is definitely not for you.
Why?
There are still tons of issues with this particular build. A lot of visual tweaks needed.
Should you still insist on installing OS X Yosemite 10.10 Developer Preview, do yourself a favor by installing it on a different drive than you working drive.
In four weeks we should see a much better build of OS X Yosemite Developer Preview.