I'd say exact dimensions are the norm for FreeCAD too - the mouse isn't used for freely drawing shapes in any workbench that I'm familiar with. With the Sketcher workbench in particular, the constraints control the geometry; the mouse is essentially used for selection and input of relationships between shapes.
They should link these videos on their website somewhere. The first time I started FreeCAD I was completely lost(well, I'm not really a CAD expert), but some videos on YouTube explain the basics really well.
Now I find the sketching pretty intuitive, albeit a bit clunky and slow. The number one feature I'm missing is the program telling me WHAT degrees of freedom are still unconstrained in a sketch.
For example (I've only skimmed this video, there are likely better ones), check out https://www.youtube.com/watch?v=rgstQi9jpGc