Editing pictures for facebook and creating comments in a forum are are not particularly "forms of creation". Photoshopping a magazine cover and building a website are.
As for photography, messaging, and gps. Well, of course. Those are a natural use for that form factor. I'm not going to take my laptop out to take a picture... (I'm kind of surprised you didn't mention that the phone is better for making phone calls too).
Sure. For a comment the size of a tweet, that's fine. I bet you're not writing long-form content on your phone, though. Or doing serious code development.
For some content creation, there's nothing that can replace a real keyboard and a real (large) screen.
The phone is now a primary photo editor for the majority of users. It's where I'm authoring this comment right now.