From what I gather the conversion wasn't a big deal. The engines of the time weren't picky about fuel, so you just have to find space to mount the wood gas generator (a very simple if bulky device) and pipe the wood gas into the fuel system. And once gasoline was available again those vehicles were easily converted back
If everything is operating correctly then yes it's wonderful. If conditions are poor then you are in for a bad time. There are a lot of things that can cause poor gas quality, often having to do with things like biomass moisture content, mineral content, and material feed. You can get into regimes where pyrolysis and reduction are incomplete and the tar content of the gas is high enough to stick valves and acidify the oil. Gasification is a fickle lover.