I have a Mac Mini running Yosemite, the latest update among other things introduced Photos. At the same time it eliminated iPhoto. In my opinion this is a bad thing. It introduced the ability to sync over iCloud which is of no value to me as I have nothing to sync. Photos is less usable, edit tools are not under the Edit tab they are under Image & much less useful than iPhoto. This seems to me to be largely changing things for no reason other than Apple know better than you what you need or want. Why could they not just give the opportunity to have a look at Photos then keep iPhoto if wished?