OpenSCAD is great for functional parts, built of basic components. It can start to be good for moderate complexity components with the BOSL library (I use BOSL2) including chamfers/fillets where needed. And the parametric/customization aspect is second to none - IF it's built with that in mind.

Where it really falls down is when you need to somehow get data OUT of the model to feed to other shapes. I would love to be able to specify a chamfer or fillet along a contact edge of two other shapes, but unless you know the exact contact shape, location, and size a priori you will have a tough time getting anything to line up. If you want to use a mesh or model as a negative, every model's zero coordinate needs to be just right or it will just be entirely misaligned.

I've also tried to spend some time performance optimizing for render/output. It is not cooperative at all. It will just soak CPU time for a minute at a time for not even a complex shape! As pseudosudoer said, it really goes off the rails.

But for functional connectors, adapters, and replicating parts, it's great to be able to leverage my software skills in 3D modeling!