The editor offers basic editing tools that let you auto-fix the color of an image, manage its saturation, contrast, and brightness, mange the light, enhance color, and apply a vignette or a radial tilt-shift effect. If you want to draw or scribble something, you will still need to use paint.
The new editing tools seem to be accessible from any native Modern UI app that can open images, which includes the Photos app itself, Camera and SkyDrive. It is likely that this revamped app will even send some third party apps packing too. I’m not sure if there was a cold war for best image editor going on between OS X and Windows, but if there was, you can all go home now Microsoft’s knocked this one out of the park with the photo editor built into the new Photos app that comes with Windows 8.1 Preview.