After upgrading my MacBook Pro to 10.10 (and then to 10.10.1), I experienced 2 problems.
First, when I used certain programs, the save dialog box would continually get bigger. So each time I saved something in Safari or BBEdit, the dialog box would get longer by a line of text or so until the bottom was off the screen. I use Default Folder so at first I thought it was a problem with that, but after completely uninstalling it, the problem remained. I figured out some workarounds, like making sure I made the dialog box smaller after a few saves, but I couldn’t resolve it. Jon Gotow, the developer behind Default Folder figured out the problem. He found that Apple changed the file dialogs so that the title bar is now considered to be part of the window—and changed the math everywhere except in save sheets. Yesterday, Gotow released a beta version of Default Folder that fixes the problem. It is a beta release but I haven’t had any problems with it. If you are affected by this bug and don’t use Default Folder, you could use Default Folder’s 30 day trial and maybe Apple will fix this in 10.10.2.
My second problem was I was no longer able to connect to the VPN service, PrivateInternatAccess.com. I could connect using PIA’s own VPN app, but I couldn’t use built-in app for L2TP VPN. I figured out that my static IP that I set for my local network broke the VPN app, both for wireless and wired connections. I was able to change the setting to “DHCP with manual address” and the built-in VPN worked. Hopefully, this will be another issue that 10.10.2 fixes. I’m sure this affects a pretty limited number of people, but it was very annoying.