This seems like it is primarily an academic/learning project but I think it could be a good way of learning UML. I especially liked this part of the philosophy - "P2. An Umple programmer should never need to edit generated code to accomplish any task. The need for round-tripping (editing generated code and then reflecting the edits back into the model) common in the Model Driven Engineering world is not needed."
It wasn't that great as a tool for learning UML. Was forced to use this in my soft Eng courses at uOttawa and it was not very helpful
Umple was a huge amount of work. The bidirectional nature of the text form and the graphical form is very impressive. However, it is fatally flawed system IMHO because it adopted wholeheartedly the doomed OOP paradigm, and when you see how many classes you end up using, it makes it hard to understand programs. But a very powerful project, and probably thousands of hours of work to build it. I would be very interested to know how many man-years were put into the program.
I like aspects of this; shame it has no C# support.