I have been using Appcoll since 2014, when my firm had outgrown a homemade docketing solution. Since then, Appcoll has become a key tool to help my firm grow efficiently.
One of the best features is its automatic import of USPTO PAIR data through XML files. It saves time, but maybe even more importantly it serves as a quality control tool. Appcoll marks any discrepancies between USPTO data and its internal data. I have found spelling mistakes between USPTO filing receipts and my docket that way before, which I would not have otherwise.
Over the years I have customized Appcoll tasks to automate, as much as possible, recurring task. Reporting a filing receipt has become a matter of just a few clicks - and the client receives an automatically generated email with the receipt attached.
In short: There is nothing I really dislike about Appcoll. Yes, there have been a few bugs in the application at times, but the Appcoll team has always been responsive and fixed those when alerted to them.
Appcoll is an integral part of managing all aspects of my firm's activities. As you would expect from a docketing system it keeps track of applications and related tasks. Beyond that, I use it as much as possible to also replace the need for an assistant: Appcoll prepares reminder emails that I glance over and forward to clients. It prepares pretty much all of my forms for filing new applications.