This was one of two books I picked up on one of my latest used-bookstore sweeps, more out of a sense of obligation than any burning desire to read it. It's so widely hailed as a classic of hard SF, though, that I feel like I really ought to read it, if only to pick up the occasional references to it. (The other of the two, for those who care, was Van Vogt's The Weapon Shops of Isher which I really don't think I'm going to finish).
Actually, I enjoyed this book a lot more than I expected to. In recent years, I've pretty much lost my taste for gadget stories, and this is nothing if not the king-hell Gadget Story to beat all gadget stories. The writing ranges from the pedestrian to the leaden, the plot never builds anything resembling actual suspense, and the technology has aged extremely badly. Still, there's something indefinably charming about a book that contains the line "Dave, put that slide rule back in your pocket, and get to a calculator."
The plot is your standard First Contact/ Incredible Journey fare. An expedition from Earth to the mysterious high-gravity planet of Mesklin has lost a rocket full of valuable scientific equipment and data (slide rules or no, Clement was prescient about some aspects of NASA's future...). The rocket landed in a region of intense gravity (gravity on Mesklin varies with latitude, from the merely high to the absurd), where humans can't be sent to retrieve it. Fortunatey, though, a scientist from the mission has made contact with (and taught a surprising amount of English to) a gang of native merchants, wo are convinced to go on an Incredible Journey to retrieve the rocket.
Sitting down to try to describe this, it's difficult to articulate what exactly I liked about this book. There's really nothing to it other than the nifty setting-- none of the half-dozen characters have any personality worth mentioning; the plot is little more than a travelogue, as nothing every seriously threatens the mission; the aliens are all too human in their motivations, and various traits of the species come and go as needed to suit the plot.
Still, for the first two thirds or so (not so much actual text- the whole thing weighs in at 174 pages), it's an amusing little travelogue. The author has clearly spent a lot of time thinking about cool tricks he can play in this setting, and they're described interestingly enough. The plot flags badly toward the end, though, as it relies rather heavily on technology that's laughably outdated.
(You really have to admire the boundless optimism of writers of that era (the copyright date says 1954). It boggles the mind to think that they really thought we'd go to the distant stars with communications technology this limited, let alone while doing calculations on slide rules...)
I wouldn't in a million years recommend this book to anyone looking for good characters, tight plotting, beautiful writing, or alien aliens. But it's a nice example of the sort of thing that the genre was built on, and it remains surprisingly readable despite the fact that, in many of its carefully thought-out technical aspects, it was passed by decades ago.