First off, I love the Doodle command. Finally, a freehand sketch in that looks decent! Hopefully this will make it into Acad sometime soon!
Now that the nice comment is made, here are some disappointments.
The claim that Project Cooper uses the DWG file format is (IMHO) much less than honest. Since PC cannot open perfectly valid dwg files created by other applications, whether Autodesk core CAD application, their verticals, or a competitors, it's not a DWG compatible application. And actually, given the apparent target market, DWG is really not needed. What would be necessary is a direct path to AutoCAD, so that Acad can instantly open Cooper files.
Might I humbly suggest a three part strategy for Cooper files. 1) DXFIN. DXF is the documented and published drawing exchange format. It's not convenient for everyone, or possibly anyone, but it gets the job done. And there's a ton of raw material for sketchers in DXF on the web.
2) Use SVG as the 'native' format for Project Cooper. It's a public standard, well documented, and would be well suited for the lightweight vector graphics that can be created using Project Cooper. IT's also usable on the web, or as a source for non-CAD graphic designers using higher end graphics applications, Illustrator, Corel, etc.
3) For that critical design migration path to CAD, add SVG import (and hopefully export) to AutoCAD.
Second brickbat: speed. or lack of. good lord people, for the little bit of stuff Project Cooper can do, it's incredibly slow. How can it be easy to use if people forget what they wanted to do by the time the program opens?
Third brickbat: Ease of use is not defined by cartoonish looking icons. It's better served with a simple interface, using logical names in a menu system. About 12000 years ago, we as a species communicated either by speaking, or drawing pictures on cave walls. Eventually we discovered pictograms, hieroglyphs, ideograms, and finally, an alphabet. It seems insane that the current bleeding edge of high technology design thinks that pictogtrams are an advanced way to communicate. I think that just about anyone can learn quickly and easily that the word "Doodle" on a pulldown menu runs a doodling command. That seems a much more intuitive and advanced input system than the concept that a wavy line on an icon will tell you its a doodle button if you hover over it long enough.
finally, i've already ranted about the file association hijacking, so I won't belabor that point.