About 75% of the time the code snippets it provided did what it said they did. But the other 25% was killer. Luckily I made a visualization system and was able to see when it made mistakes, but I think if I had tried to vibe code this months ago I'd still be trying.
(These were things like "how can I detect if an arbitrary small circle arc on a unit sphere intersects a circle of arbitrary size projected onto the surface of the unit sphere". With the right MATLAB setup this was easy to visualize and check; but I'm quite convinced it would have taken me a lot longer to understand the geometry and come up with the equations myself than it actually took me to complete the tool)