Great concept and it does what it's intended to do. However, the UI could use some work. Switching between conversations is somewhat cumbersome because you have to scroll through your entire list of contacts to find the conversation you want. It would be better if each conversation were displayed in a thread, similar to your standard text messaging app. I like that I receive a notification for each individual person commenting on a group chat, but I wish that they would all clear one I opened one of them. Lastly, if you click to call someone, it displays their phone number. If one of the main points of the app is to keep that information private, it's missing the mark there.
Works for me flawlessly.