Cipher is a great tool. I use it to do some mentalism to start out my set and then move on to other things. Later in my set I use something that Cipher has allowed me to know in a very nonchalant way. Almost everyone catches the seemingly impossible information I've "devined" and they freak out, but I just move past it as if it was nothing.
If you use it wisely, Cipher can be used to do some really cool effects. I'm a huge fan of it. Also it's a nice little thing that you always have with you since you have your phone, so it can be used for some fun impromptu tricks.