>> It is missing a few things, like selecting a face won't let me draw on that face

That's issue #423. https://github.com/solvespace/solvespace/issues/423

There isn't always enough information to create a new sketch plane, but often there is. It would probably be confusing to allow it on the sides of an extrusion but not the top and bottom. The changes needed to carry the extra information would break file compatibility, but I'd like to do a number of such changes all at once some day not soon.

>>FreeCAD spits out cryptic errors in a big log at the bottom that's pretty useless, but Solvespace tells you exactly what's wrong (generally)

I hadn't thought about error messages as a selling point, but I'll try to continue the trend of being informative.