Photos is more powerful than iPhoto in editing. With the new extensions one can use any 3rd party editor of your choice in your Applications folder from inside Photos.
It does take a bit of getting used to not having Events. However,
Moments in Photos are the new Events, i.e. groupings of photos sorted by date taken.
When the iPhoto Library was first migrated to Photos there is a folder created in the sidebar titled iPhoto Events and all migrated iPhoto Events (which are now Moments) are represented by an album in that folder.
To open the sidebar if it's not already open use the Option+Command+S key combination.
NOTE: It's been reported by several users that if the Event albums are moved out of the iPhoto Library folder in the sidebar they may disappear. It's not widespread but several users have reported that issue. Therefore, if you want to assure that you keep those Event albums don't move them outside the iPhoto Events folder.
There's a way to simulate events in Photos.
When new photos are imported into the Photos library go to the Last Import smart album, select all the photos and use the File âž™ New Album menu option or use the key combination Command+N. Name it as desired. It will appear just above the iPhoto Events folder where you can drag it into the iPhoto Events folder
When you click on the iPhoto Events folder you'll get a simulated iPhoto Events window.
Albums and smart albums can be sorted by Title, by Date with oldest first and by Date with newest first.
There are a couple of deficiencies in Photos (in my opinion): 1 - can't change the background for viewing images to a darker color and 2 - limited location editing.
The limited location editing is bound to be improved with each new version. If enough users complain about the background color it also may be addressed.
Photos has some new and powerful syncing capability between other Macs and mobile devices, i.e. iCloud Photo Library. I'm not a fan of it but with additional purchased iCloud storage you can have your entire library available on all your devices using the same iCloud ID.
Like any new paradigm it takes a little getting used to. I have several test libraries that I use to try out the different features and experiment with.
If you upgrade to Yosemite or El Capitan you don't need to use Photos. You can still use iPhoto if you had some version of iPhoto 9.X on your machine at the time of upgrade. Go go the App Store and get 9.5.1 for Yosemite and 9.6 for El Capitan. I still use both types for comparison and helping others.
