The Dymaxion car he came up with was a spectacular flop. Looking at it, I can not figure out what the heck he was thinking……
I did think the geodesic dome was a clever design until I was involved ( in a very small way) in the attempted design of repair equipment to service the skin on the one at Ontario Place in Toronto Canada. It was not designed to be worked on, and even the weight of a couple of repair people on it could cause major issues, let alone cantilevered work staging. There was a tremendous amount of unusable waste place inside, too. Funky but not too practical.
My colleagues at Honeywell who worked on the HVAC system for the OP dome used to talk about what a nightmare it was to heat and ventilate a base-truncated sphere. One guy got visibly agitated if RBF's name was mentioned – he sat in on several meetings with RBF during the Ontario Place dome's teething troubles, which I gather were less than productive.