Another plus is that Viewmatic images can be shared across multiple social networks, including ones it doesn't fully support. "Open in another app" prompts Tumblr and Dropbox on our phones, which is supernifty for backing up images.
Our takeaway? Complete control over photo editing makes Viewmatic definitely download-worthy. If you have filter regret, then you can go back and edit the image in Viewmatic at any time, without having to start over again. Sure, it's not as instant as other photo-sharing networks, but it isn't as cookie-cutter, either. Viewmatic offers iPhoneographers more flexibility and more options for creativity with their photos. There are endless recipes for frame, filter, and viewfinder combos in the app.
Our one complaint is that you can't take photos from the app itself.