Installed Yosemite DP3 on my MBP on Tuesday. Stable enough for daily use except for a few minor issues :

Safari Tabs is a bit bugg, not showing at times..

Activity Monitor crash on launch

Dual screen causes the new transparency effect on windows to flicker (Just on Safari)

Other than that.. 10.10 is more refined than 10.9 in some ways. Loving it!

Depends on how big the file size are. Large photoshop files requires at least 8GB to load properly. 4GB is doable but will encounter some slow downs. 4GB is the bare minimum for general Photoshop usage.

Received my invitation to the Public Beta this morning. The release will be the same as DP4 but with slower updates compared to the Developer's Preview build.

Unfortunately the Dark Mode isn't as optimised as the normal. There are still pixelation issue on non-retina screens and developers have yet to update their menubar related elements to make full use of the dark mode

Cant wait for the retail release. Loved 10.10 so much