After reading about all of the unhappiness with the new Photos app, I held off on updating to 10.10.3 until last night. I was under the impression that one could install the OS X update and that Photos wouldn't import one's photos until the app was first launched, but that was bad info. Something called "Photos Agent" started hogging my CPU usage as soon as the update was completed, and it turns out it was importing my pictures to Photos without me even launching the Photos app. I still haven't launched the new Photos app, but when I launched iPhoto a minute ago, a dialogue box appeared that asked me which photo library I wanted to use (I have only one), and then it warned me that my photos have already been imported to Photos and that any changes made in iPhoto won't appear in Photos. As mentioned in other threads, I still have a lot of work I need to do in iPhoto. Specifically, I need to add location info. to hundreds of pictures before I transfer them into Photos, which at least for now lacks the ability to add or edit location/GPS info. How do I start over as far as Photos is concerned? If I simply delete the "Photos Library" file from the /Pictures folder, will that cause a complete re-import of my iPhoto library if/when I launch Photos, or have my photos physically been moved into that file/directory, and deleting the file means I'm deleting my photo library? Thanks for all feedback.