Insta Blur allows you to use your finger as a spot-by-spot filter for your images, applying blurs and other effects that are available in the app. While the app is well constructed, has a decent interface, and is very responsive, it lacks a deep feature set, which can limit its usability.
When you turn on Insta Blur for the first time it is ready to use. Load the app and start applying edits right away by choosing from the two filter options that come in the free version -- blur or mosaic. The other two are paid upgrades and offer new options like dots and polar. There's no "Undo" button, but you can switch to the eraser and swipe away any changes you've made to that point. You also can change the size of your brush, but not the intensity of the effect and you can share at any time with the different export options. The sample photo is a great one to test your editing skills with and the page can be reset at any time using the erase option. The interface is clean and doesn't offer any extra, confusing options, but the lack of features can limit how useful the app will be.
If you need an app for selective blurring of your photos, Insta Blur will get the job done, but not much else. It only provides two filters for free, and another two if you pay for an upgrade. The lack of features hurt the app here, because if it had more filters, more ways to edit and adjust filters, and better editing functions, it would be a more useful app in a number of situations. As is, it is a decent free app with limited applications.