You just convinced me to give Photos another chance. I absolutely hated it when they gave up on iPhoto and Aperture because I felt like I lost a lot of features if I moved to Photos. Ever since then, though, I haven't found a photo solution that works quite as well as any of the Apple products I've used in the past so I'm willing to give it another shot.
Photos.app is atrocious from a UI perspective. It's an iOS app shoehorned onto OS X. How to back up your library to, oh, I don't know, an external disk? Drink the kool aid or else.
What? The UI is totally fine. Just because it's a grid of photos doesn't mean it's just "an iOS app shoehorned onto OS X." The app is written from the ground up for OS X. It's not just some basic half assed port of the iOS version. The UI is different. The editing tools are more powerful. The performance is blazingly fast. Go give the Photos app on Windows 10 a shot if you want to see what the competition is up to. That is a pathetic Windows (mobile) 10 port.