My main complaint is that history management in FreeCAD is poor, and the ability to assemble parts is very, very limited currently.
That is: create a sketch, extrude, and fillet 2 edges at random. FreeCAD seem to use some incredibly naive edge enumeration technique, which breaks instantly as soon as you add/remove edges from the underlying sketch. This makes design revisions almost impossible currently, which is the primary reason you use a parametric cad for.
OpenCascade in itself is not as bad as people make it to be. It's a bit buggy, but not drastically more so than fusion 360. In fact, you learn to work around most geometric kernel issues in any parametric cad with time. All of them have bugs and corner cases. OCC itself has never been a limitation for most of my designs.
FreeCAD combined with CadQuery is immensely more powerful than most commercial offerings I've tried. I dream of being able to interleave CadQuery and FreeCAD sketches at any point in history to prototype!
I found this youtube video to be a great primer (and wished I had it a few years ago): https://www.youtube.com/watch?v=3eWlU2Ddl6I
Also, last time I checked (about a year ago), it didn't really have a way to create assemblies from parts.
Most people recommended Fusion 360 but I personally found it a bit annoying to work with, especially seeing that it's basically a webapp. I wanted a real native app to work with, so I went ahead and downloaded FreeCAD. It's also open source and seems to have a thriving community.
Anyone else got some opinions or experiences to share on FreeCAD for beginners?