Pros:
Arsenal is the only opportunity for discing within walking distance of the Cambridge area. It's also easily enough accessible from a larger portion of the city via a combination of public transit and walking.
The area seems very well kept; grass was cut and there was little threat of schule. The baskets were in good shape. There are enough trees and even a bit of elevation to create some adequate safari holes.
Cons:
Regardless of what this course used to be, it's hard to consider it presently as such. There are no tee signs or apparent tee boxes, and only five baskets remain from what I could see. Two of these are ~40 feet apart, one sits at a very awkward junction between a walking path, some hedgerows, and a parking lot, and two sit along a hillside that is only one griplock or rookie mistake away from a major road. Pedestrian traffic seems common, and a children's playground forms a major obstacle near the closely-situated pair of baskets. It was unused the day I was there, but in times of use it rules out playing 2/5 of the remaining baskets for anyone with even a flicker of good sense.
The feel of the course is as though the ample buildings and parking lots around it sprung up subsequent to its creation, eliminating holes and making still-present baskets basically obsolete. From prior reviews it seems as though the course was built around such structures from the get-go; this layout was done in such a way so as to eliminate even casual play and conflict with parking and pedestrians. With several baskets removed and any signs of a formal layout gone, the course doesn't feel like one at all. In a just world the remaining baskets would find a better home within the area, where they could be put to use.
Other Thoughts:
A 0 rating seems harsh, but this course feels so far below even the 0.5s I've given out that I feel justified. It's not a course. You can practice putting and throw around a bit, but that tires quickly given the constraints of what's available. It's nice to be able to bag a course in the Boston area, but that's the extent of what you'll get here.