"Welcome to Google Photos, the new home for all your private photos. The photos you've shared on Google+ are still available in the photos tab of your Google+ profile."
The message links to https://plus.google.com/me/photos, which is the photos tab from your Google Profile. Until now, Google Photos linked to Google+ Photos, bypassing the redirect.
You can still go to Google+ Photos using this link: https://plus.google.com/photos/highlights, but I don't know for how long. Most likely, Google+ Photos will disappear soon.