I tried to draw a part from some reference sizes today and found it very difficult because I was unable to add some constrains and dimensions. I've drawn the part in another system very easily here are some of the problems.
1. No perpendicular constraint to a circle. Example from other program.

2. No dimension from a line to the circumference of a circle or between circle edges.

3. No automatic projection of axis when adding dimensions or constrains.
4. Automatic projection when dimensioning would be more useful if the lines created were construction lines.
5. A way to draw construction geometry without having to draw as normal lines first. Maybe a toggle so you either draw normal or construction.
Mark