Not going to be my final star rating just yet hopefully, but there's a SUPER-ANNOYING glitch where if you talk to Yupa, the game freezes and you can't do anything. The music continues for a while and then even that stops. Seems to happen to me after he talks about how economical it is to stick lots of Yupa on a lorry. Irritating because you have to get fairly deep in the game for this to happen and it has struck me twice! (Third time I tried it I remembered to save the game first - yeah the conversation with Yupa is definitely what triggers it!)
A minor thing, the retro-mode switch toggles from OFF to OFF? It does switch successfully though!