Funny, I've actually installed Circle the other day, after receiving multiple requests from friends over facebook - and hated it. Initial problem was, the options of logging in where through Facebook, twitter, or email - but the email option said it would take up to 24 hours to approve... really? and it didn't seem functional - so i had to choose between twitter or Facebook. The user interface kept jumping from one style to another between login options, making it look non-legitimate. It also got my location wrong, with no option to change it (I'm on the border between two cities) showing me events that where too far. I was so frustrated with it, I un-installed it within 10 minutes - so I still think theres a market for an app like this, Circle is doing it wrong.