The simplicity of the system. It's easy to use, and it works as is supposed to. No customization needed. The program is a simple drag and drop system, so the ability to customize was not needed. The interface is easy to understand. It also integrates with other apps, so I had no problems with that. It is very simple to use, so it is not a big concern for me. I am working on a proposal for a friend who is in the real estate business. I am helping him to create a proposal for a potential client of his. It is very easy to use and it makes collaboration with other team members very simple. I have not found any drawbacks so far. We are using this software for our internal projects, where we manage tasks and milestones. It is also used by our external partners to send us their project updates.