Apple released the 10.10.1 update for Yosemite yesterday. It is about 312 MB and can be downloaded form the Mac App Store and installed. I do not have automatic OS installs turned on so I installed it manually on my 2012 iMac. Here is what it looks like:
When you do the install Yosemite goes into a restart mode and downloads the update like so:
As is usually the case in my installs I ran Permissions Repair using the Disk Utility app and then did a normal restart. All seems to be running well. No problems at all.
Apple says the update fixes some WiFi issues and a few other things. Here is a link to what is supposedly repaired. At this point I would say go for it, seems to be a stable update.