I've been experimenting with Photos to discover how I would fit this new application into my existing workflow. FWIW, I'm an abandoned Aperture user...who has spent significant time investigating the likes of C1, LR, RT, Iridient, etc. to find a new "home." Since I was delaying my decision until Photos was released I can now rest easy with my conclusion to stay put with Aperture until they pry it from my cold dead hands. All of the other tools offer something compelling...but (for me) none of them provides the whole enchilada as competently as Aperture.
As some of the others have noted, there are some "real" tools in Photos...and it's clear (to me) that Apple made an effort to provide "enthusiasts" (not including Pros in this category) with more than just a "one click enhance" type feature set. For me, the big question is if Photos will provide hooks for 3rd party applications and integrated 3rd party tools. The inclusion of a healing brush gives me some hope that one day there will be a mechanism to apply more local adjustments within the Edit interface. On the whole, I continue to be impressed with the RAW rendering capabilities that Apple provides (the RAW support in Aperture uses the same libraries as Photos). I can still get great looking images out of Aperture...but the one area it really falls down is related to noise suppression.
As is the case with most 1.0 releases, there are some missing features in Photos (geo-tagging) that I imagine will come soon. There are some really nice UI improvements (assigning Faces), and the "ubiquity" that Photos plus iCloud provides is pretty awesome...and it's clear that Apple's vision to provide access to all your photos on all your devices is finally coming to fruition.
For now, I'll continue to manage my library in Aperture, and will PP the majority of my images in that application...but will fire up RT, Iridient, or C1 when Aperture can't produce the results I want. I'll likely use Photos with iCloud to share all my DSLR keepers (exported JPGs from Aperture, etc) and Phone pics.
One day I'll need to abandon Aperture...but that day isn't today. For what it attempts to do and be, Photos looks promising, and I'm interested to see how it evolves regarding library organization and management. Ideally, Photos will provide a way to select an image and "Edit in..." or similar functionality. If, in a few releases, it ends up being a good DAM that can sync images across all my devices...and provide decent editing capabilities (with the ability to edit externally, if necessary) I'll have found my Aperture replacement.