The first thing i noticed after running the Photos app is that some of my smart albums all had the same thing... all photos. Then i checked, and realized its because as the new app has no "events"... and those albums used events as criterium for inclusion... they basically reverted to using all photos. So i'll have to manually go in to all photos that had appeared in those albums and figure out some other method of limiting. Second... i've read some of you on here say that the two apps should now exist separately on my machine. In the Pictures folder there does appear the iPhoto library and the Photos library. But i've read people saying that the new app just uses hard links to the files that are in the iPhoto app. So this would suggest that you can't delete the older iPhoto library, right? And i checked size.... the iPhoto library is 31GB, and the new Photos app library is only 19GB. I've always wondered why my computer is running out of space, and it seems that iPhoto is perhaps bloated? (i've always avoided doing any editing in iPhoto, to avoid creation of duplicate copies of a photo, but seems perhaps has happened anyway?). All i got so far.