I have been using this app for about 2 months for work. I have a boss who can be very hard to reach , especially by email where my message gets lost with all the other emails he receives. Using a room where we are the only participants, I often get things approved the same day because he gets a notification when I add a post (kind of like Twitter). The app is very intuitive and easy to use. Using with my other colleagues, I have cut my email use for work almost in half. The biggest challenge is getting email diehards to use Spark rather than sticking with something familiar, even if its inferior. Old habits die hard.