It took me a long time to get ahold of this book (I finally received it as a present!) Don't wait as long as I did to read it - this is a great book. It's certainly very different from the epic fantasy that Martin has become best known for, but fans of Martin are aware of his breadth of styles.
The book collects stories about Haviland Tuf, Ecological Engineer (and cat lover), that were originally published separately, but they come together as a coherent novel.
The first section is a classic "subtraction" story. Tuf, a minor space trader, owner of the ship 'Cornucopia Of Excellent Goods At Low Prices', is hired by a diverse group of disreputable types who suspect they know where to find untold booty - an intact 'seedship' of a defunct Empire, more powerful than anything now known to the galaxy. Unfortunately, disreputable characters tend to behave disreputably, and soon infighting and plots occur. Due to a combination of ingenuity and luck, Tuf ends up the sole owner of the ship, and sets himself up as an Ecological Engineer, available for hire to fix any sort of planetary problem.
Although he has a variety of comissions and adventures, he keeps getting called back to the planet of S'uthlam, a place (over)populated by a 'nice' but religious people who believe it is their manifest destiny to breed as much as possible. In the past, this has caused major problems with their planetary neighbors, who don't care to be overrun by S'uthlam. Now they are confined to their own planet - but they are running out of food and resources.
Tuf helps with improved agricultural strains and methods - but this just enables the S'uthlam to breed more rapidly. The hard-headed, tough Portmaster, Tully Mune, who knows her people have an even more serious problem than they realize, has to keep calling Tuf back... and drastic problems may call for drastic measures.
This book is clever, funny, entertaining - and also deals deftly with some of the most serious problems that we here on earth have, much like the S'uthlam, refused to engage. More than anything else I've read lately, I keep finding myself talking about this book to other people.