I've been using MSP for over two decades and have found it to be a wonderful scheduling tool. It is really valuable when you get stakeholders round a table to discuss a proposed project. It is able to allow the user to quickly add activities, resource, link and define work patterns while the stakeholders are brainstorming. At the end of the meeting you have a planning schedule, rather than someones recollection of comments. The advantage is the ease of the user to quickly keep up with the conversation and input data. Other packages need to have structure already established before adding activities. It is important to not frustrate the stakeholders by slowing up their thought process with slow data capture due to the software limitations. I use MSP to collate peoples thoughts into mini schedules and then import this into P6 for portfolio management. Best of both worlds.