I love all of it! It's simple to use & fast for sending messages back-and-forth between team members as well as communicating internally within our organization (we're an agency). The ability to have multiple people work together from different locations simultaneously has been great because we can save time by not having everyone physically present at meetings or events where they would otherwise be required to travel/be there. We've also used Fastee during client engagements when working remotely with partners who are located far away - so much easier than trying to get calls transferred via conference call bridge software etc. Nothing yet but if you need something quick then this works perfectly. In my experience nothing too specific but just general issues like slow response times. If your looking for something easy to implement into daily workflow without needing additional resources this could help out quite.