The trick with holes is to make your negative geometry penetrate past the surface. Meeting exactly on the surface will be too glitchey otherwise with the fast floating-point approximation.
Fillets and chamfers though, yeah. The lack of those drives me away. As Quinn (Blondihacks) says: "Chamfers are what separate us from the animals.", and as This Old Tony says: "When it comes to chamfers, you don't want to cut corners." (And if you don't know who I am quoting, you clearly don't waste enough time watching machinists on Youtube.)
Chamfers can be done by extruding the chamfer shape along a wireframe of the geometry to be chamfered, then subtracting the extrusion from the original geometry. I'm not sure how I'd do fillets in OpenSCAD, though.
You can use a Minkowski sum to give yourself a fillet. I did it once. It worked but was 2x as hard as learning enough Fusion360 to do that whole part and then each design after that is 20% as hard.
I eventually got pretty good at OpenSCAD, but I’d say I now reach for OpenSCAD about 3x/year and everything else is in Fusion.
I either live without, or get creative with use of hull, cylinder (including cones), making toroids by radial extruding circles (using the toroid as a cut shape just to get a fillet around a post), or I just open the scad file in freecad, and then apply the fillets in freecad.
It's definitely a weakness in the sales pitch having to work that hard for something you want that often.
All of my scad designs include an o=0.01; or 0.001, and all it's for is for prepending or appending to other values and expressions all over the place so that cuts and joins always overlap at least a little.
As a mechanical designer who has quite a bit of machining experience, I'm the person sounding like a broken record about chamfers when doing design reviews. Blondihacks quote will be going straight into my repertoire of quotes.
Fillets and chamfers though, yeah. The lack of those drives me away. As Quinn (Blondihacks) says: "Chamfers are what separate us from the animals.", and as This Old Tony says: "When it comes to chamfers, you don't want to cut corners." (And if you don't know who I am quoting, you clearly don't waste enough time watching machinists on Youtube.)