I used Final Cut Pro/Final Cut Studio for years. When Apple switched to Final Cut Pro X I was really shocked with this vivid downgrade. But 3+ years later, with a lot of professional feathers added to the early version of FCP X, I came to conclusion that workflow in this 'downgraded' program is fast and comfortable, and practically nothing of abilities is lost (and a lot useful is added). I hope after several upgrades Photos will become closer to Aperture than in this early version. What I like in Photos right now — it's speed and automatic synchronization with iPad/iPhone library. But I'll wait for upgrades of Photos — using Aperture as long as I'll be able to to this.
For Windows only... It means — useless program for the most of photographers.
Upgrade of iMovie to professional level. Really good for broadcasting, especially for news reels. Fast and easy!
But for any kind of film/video production it's an obvious downgrade.