I read Krumnagel because it was proposed by my book club, rather than necessarily something I would have chosen myself. Overall I found the book wryly amusing rather than laugh out loud funny. The series of misunderstandings that result in the many twists and turns are deftly handled if resolutely implausible - I particularly liked the consequences of his suggestions to his fellow prisoner. I also found entertaining the assumption that real decisions are made over lunch in the members' clubs - apart from the fact there would now be more women, this aspect of the book does not feel outdated at all (sadly). However, sometimes it feels like Ustinov is delighting so much in his manipulation of the language that purely telling the story takes a back seat - and I found I had to re-read some passages to understand what was being said.
Krumnagel himself is not a particularly sympathetic character, but by the end of the book you find yourself rooting for him - simply because the rest of the cast are so much worse! I won't spoil the ending, but I didn't see it coming, which is always a bonus. Some parts of the book felt more dated than others, but the underlying theme of misunderstandings between two cultures that share a common language, but at times little else, still has relevance even in the internet age.