JEFF CARLSON, MACWORLD:
"Photos for OS X is a free update that arrives with OS X Yosemite 10.10.3, so the question isn’t whether to install it or not. Should you use it, or continue with iPhoto or Aperture for the time being?
"By necessity, Photos for OS X is an application that arrives with a multitude of compromises. It needs to replace iPhoto for millions of people whose photo libraries are stored in Apple’s default consumer photo application. It also technically replaces Aperture in the sense that Apple will no longer offer that professional app. And it has to also embrace the mobile reality that Apple itself created by making iPhones and iPads camera replacements for so many people.
"If you’re coming from iPhoto, Photos is definitely a step up. It’s fast, it has improved editing tools, and even the loss of star ratings can be worked around (though I’d like to see them return).
"If you’re a longtime Aperture user, Photos is definitely a step back. Or rather, it’s the clear signal that says it’s time to look for other professional photo pastures. I can’t recommend Photos as a full-time replacement, although I can envision situations where it would work alongside Aperture, such as creating small libraries for sharing with clients who don’t own Aperture (both iPhoto and Aperture can open a library after it’s been converted, but edits don’t sync).
"And if you’re new to the Mac, drawn to Apple’s computers after experiencing the iPhone or iPad, Photos for OS X will be immediately familiar, and even improve on your photo experience with better editing tools and iCloud Photo Library syncing."