Photos for OS X is such a huge improvement over iPhoto and Aperture this makes sense. It's just incredible that Apple is going to be giving away the world's most advanced photo application. I hope nobody complains.
This is just so blatantly incorrect, and I would imagine that it comes from someone that has not yet used Photos, and certainly has not used Aperture to its full capabilities. I have yet to use Photos as I am not part of the developer program, so I am only basing the following on the many reviews I've read along with the available details that are on the Apple site.
If you consider photography to be the mobile photos taken from your smartphone, which is perfectly fine if you do, then Photos/iPhoto are likely more than sufficient to catalog and (lightly) edit your photos. However, if you have are a photo professional and/or advanced hobbyist, then a tool such as Aperture (or Lightroom) cannot in any way shape or form be substituted with a lesser program as there are simply too many mandatory tools and capabilities missing. Hey, dentists use drills, but they don't use a DeWalt drill with a 1/2" drill bit!
And yes, I know that Apple did not say that Photos is replacing Aperture. They didn't have to. They are discontinuing development of Aperture, which will leave those that rely on it to find an alternative at some point (immediately, or once it no longer works properly with the OS, or once new cameras are released and RAW conversion is not supported, etc.).
Keep in mind that Aperture "files" are in to way like other application files (Excel, for instance). They cannot simply be opened in another "compatible" program like Excel files can be opened in Numbers with (most) everything still working properly. Aperture libraries cannot be completely migrated to any other program and maintain all facets of the data. It is a fact. Any migration of an Aperture library to another DAM will require compromises at least as every DAM works differently.
So the people that are complaining about the new Photos app are most concerned with the need to (eventually) move countless hours of work, tens and even hundreds of thousands of photos, to a new platform, and even still lose the non-destructive edits that were applied to those photos. It is a big deal, and has nothing to do with the $80 that was spent on Aperture (in my case several years ago, I more than got my money out of the program). It is about losing (eventually, sooner than later) an important tool that is integral to photography work.