My biggest gripe with SolveSpace won't let you write code, everything is done in the UI which is very limiting and a big turn-off, especially given what the underlying geometry engine is capable of.
On the other hand, OpenSCAD doesn't have a constraint solver (you can't easily say something like "compute the intersection of these two circles and project the resulting point on this surface and extrude a cylinder from that point along the normal of that surface"), whereas SolveSpace does, and it's a very powerful way to model things.
OpenSCAD is also very annoying in the sense that it doesn't allow you to "probe" your model to construct it further: it has exactly zero self-introspection features. To give a simple example, it's almost impossible to compute the bounding box of a model or its barycenter, which is very limiting.
Solvespace 3.1 (due soon RC1 is out) will allow linking STL files, so you can do your OpenSCAD stuff that way, then link in the STLs in solvespace. Not sure how useful that's going to be but it's something for those who like both tools.
Actually, I chose it over Openscad for one reason — it doesn’t crash that often)
Otherwise it’s a bit less flexible — e.g. it’s harder to do value constraints (e.g get dimensions from a spreadsheet);
and it isn’t compatible with scripting yet;
you can’t just point-click-chamfer your parts;
you need to do metric holes and indents for bolt heads manually;
etc, etc
But what is available works almost without any problems (except for 3D constraints and occasional problems with difference operations on curved surfaces) — and is soo fun to use.
