It is a little rigorous in its methodology and is cumbersome. For example, I have a hard stop date and I would like a project to end by a specific date, but this is not how this solution works. It sorts of spits out the project date based on your resource availability, dependencies, and so on. This sort of project planning works in theory, but that's not always the case.
It also relies heavily on resources entering their time into the system, that is, how much time they worked on each of the tasks so that it can sort of consistently update the project. I know that in a lot of organizations, including ours, it is almost impossible to get them to track the time.
In terms of additional features, they can include more integration with Microsoft because integration is going to be a key functionality.