Book. Because:

• funnier (Douglas’s thoughts – dry, pointed, and ultimately misinterpreted when he speaks, are great on paper, but are a little lost on the screen).
• there’s context in the book for Douglas’s anger, and as a result readers will be more forgiving of him than viewers.
• flashbacks are always better read than watched (although at least different actors were used for the main characters’ younger selves).
• descriptions of the European cities the family visits are magnificent – accurate and humorous – whereas the TV series relies on visuals, and misses the quirks.

Book here. TV series here (on Foxtel in Australia).