Just used this to make a couple quick diagrams. It's easy to use and the diagrams export well. A couple suggestions for improvement:

1. When working with small rectangles, I had trouble getting the rectangle to move instead of enlarge. It looks like holding down the mouse button for a second makes moving more reliable. The UI should make it clearer what I'm actually doing.

2. If I open MonoSketch in another tab, I can't make a second diagram at the same time as the first -- there seems to be one shared context between tabs. I would like to be able to make a new diagram separate from my current one.