They're everything they've been cracked up to be.
I remember opening the Pinto & Custom Painters kit I bought on eBay in '99 or so, and the disappointment shortly thereafter. The locating pins on the windshield were huge, the body had way too much roll at the rockers, and the nose and fenderlines seemed very "square". The figures are great, and the best part of that particular kit IMHO. Bell bottoms, pointy collars, and a 'fro scream early '70s, but the head can interchange with the F/C Drivers' bodies, making them even more versatile.
The F/C Chassis (mine was a swap meet glue bomb buy) set had some nice details, but since the chassis is molded in one piece, the tubing is only half round. Good for a quick glance, but not nearly as realistic as the Revell 1/16 F/C and T/F kit chassis. The M&H tires are phenomenal, the 5-spoke American front wheels sensational, and the Donovan 417 is in a league of its own.
Hard to believe they didn't sell.
According to Tom West's History of Drag Racing Models which ran in SAE in '90 or so, they didn't sell well at all.