Phoster is a free universal iOS app that is really one of the most useful and clever photography-related apps I have seen in a long time. The app creates posters and invitations that look like they were professionally designed, yet the base elements are provided by the user. There are 197 different templates, all tastefully done and easy to modify.
To begin, you insert photos from your camera roll, or take a photo on the spot from within the app. Phoster lets you vary the background colors and the size, color and fonts for text, and add filters to further customize your creation.
The output of the app is very clean and is sent to your camera roll or shared via email or the usual social networks such as Facebook and Instagram.
Using Phoster is easy. There is built-in help, but most users won't need it. Some reviews have mentioned crashing, but I personally found the app to be very stable.
There are a couple of improvements I'd like to see. This is yet another app that forces portrait mode, and it should also work in landscape orientation. Some of the templates are actually in landscape, so it seems counterproductive to force portrait view. In addition, once a poster is saved, it can't be edited. It would be nice to be able to reopen a saved poster and continue to work on it at a later time.
Output resolution from my iPad 3 was very good at 2,896 x 4,096. Older iOS devices will see resolution reduced, but they'll still get results that will print beautifully.
If you have a need to create posters or invitations, this is really a terrific app. Since it's free, it's a no-brainer to pick up Phoster. The app is optimized for the iPhone 5 and requires iOS 4.3 or later. Phoster is highly recommended.