Not the best but kinda works...

First thing that happens when I upgrade to 10.10… You need to buy this because apple. Then I buy this because apple. Then you install the new os x server and then suddenly you can never access your server remotely using the EXACT same OS and the EXACT same server.app. Even when I restart the server and the checkbox that says “allow remote administration using server”. Yeah thanks for another update that fixed nothing and yet broke even more of the stuff I spent months trying to get working again. TBH OS X server is hard to work with if it’s never programed correctly. If I could warn anyone, it would be that you all should wait for a few updates before upgrading all your servers to Yosemite becuase if you do you have to buy this which will break a few of your services. Apple you really need to step up and work harder with this server program, otherwise it’s just going to get worse. But now for the Good parts of this that put it to 3 stars.
Install and upgrade is fast and easy like always and updating is easy too, Most services work correctly and the server still at least works but some of the things apple added could still use some work but the looks of the server app have not changed either and apple also has been adding to the security of servers and has added an option to only allow certain users from certain connections (Public or Local) to use the server. So that’s a little plus side.

Long story short: Don’t buy this upgrade, yet… Wait for a few bugfixes and updates until you upgrade.

Mitzey234 about macOS Server, v4.0