And essentially, that's it! You take pictures, you add a place and/or time caption, and you send it off! It's incredibly easy to use and can be a fun and simple addition to a picture. The app comes in a paid version ($1.99) and a free version (with ads and less skins).
As for educational uses, blogger Jamie Forshey at EduTech for Teachers has been writing about her ideas for a while, and her blog is great for resources. Personally, I think it'd be an awesome tool for sending older students on a virtual scavenger hunt. Imagine sending kids to all the historic locations or landmarks in a city, they could easily use this app to take a picture and prove they actually went there! Plus they'd have a fun keepsake from the adventure.
As for suggestions, the only thing that might make the app more enjoyable and/or useful would be the option to allow users to create custom skins. Then, teachers or students could create a caption with a question or fact to send out to the class via facebook or twitter and other students could respond. Otherwise, the app does what it set out to do!
In conclusion, InstaPlace is great for what it is: a simple app to add location-based captions to a picture. Will it revolutionize the way you teach? No. But with a little bit of creativity it can be an enjoyable tool in the classroom.