While this adventure/spy novel wasn't particularly tense or exciting, it's short enough that it didn't get too dull.
To a modern reader, used to double agents, moles, and triple-crossers, the plot seems rather straight forward, and Rochard Hannay is no James Bond. Despite being the hero, he doesn't actually display that much ingenuity; most of his escapes are made possible by random coincidence and the good luck of meeting a lot of ridiculously kind and trusting folks. One aspect I did enjoy was his disguises and quick-thinking when it came to inventing a new persona. He's no action hero, nor genius, but he can talk himself out of a tight spot, and all in all he's a decent, likable guy who does have a certain talent.
The other part of the novel that appealed to me was the Scottish setting and moorland descriptions, and being able to recognise places near where I live. But for anyone who tires quickly of barren Scottish heaths, I'd warn you to stay away from this! Probably half of this 100 page novel is taken up with Hannay running around and hiding on the moors, reminding me of the first part of the last Harry Potter book.
All in all, it's worth reading if you're interested in either Scottish literature or the origins of the spy genre, but I don't think you're missing much if you decide not to bother.