Similar to when Mavericks was released, initially Lync would not pull the GAL down until Microsoft updated it in March 2014 with a fix.
Deploying Lync 14.0.11 now with a 10.10.3 or to 10.10.x users in general (mostly 10.10.3), Lync installs properly, brand new users can sign in no problem. The only problem is it is not pulling the GAL down from the server (like the Mavericks issue) so no one can search for contacts. If they are a new employee, they are basically out of luck.
Has anyone else seen this? 14.0.11 does, however, pull the GAL on 10.9.x with no problem. This is just on Yosemite clients.