The artwork is well up to the usual standard of excellence of the later Tintin books, with some great cinematographic angles. The plot is also action-packed and exciting. There is not as much humour as normal, and what there is is rather subtle (Rastapopoulos, in a tacky pink cowboy suit, vying for "who is the baddest" with miserable tycoon Lazslo Carreidas). I somehow found this book to be lacking in warmth. The extra-terrestrial theme may have been popular in the late 60s but now shows its age, and doesn't seem to suit the style of Tintin books.