Firstly - the strengths of the book. As with most Lonely Planet guides, it does provide a reasonable guide to the major areas, paticuarly Phnom Penh and Siem Riep. I stayed in a number of recommended guest houses and found them to be pretty decent and the maps, transport guides, saftey advice etc. mean that this book is probably advisable for people traveling to Cambodia for the first time.
However, many travellers in Asia who I've met have commented that 'there didn't seem like there was much to do in Cambodia apart from Siem Reap and Phnom Penh', and this (I believe) is probably a result of 'lonely planet syndrome'. Beyond these two destinations (and a few on the coast near phnom penh, the book treats the rest of the country very briefly, which may leave the impression that these areas aren't worht visiting. Evidently, this is because these areas simply are not touristy - and is what you'd expect from a guidebook like this (so no discrdit whatsoever to the author). But, all I'd say is don't let this put you off. I spent three months travelling the country, largely following reccomendations from locals as I went, and found many areas barely mentioned in the book but which were more than worth exploring. For example, a highlight of my trip was a trek in Botum Sakor national park, an outstandingly beautiful (and large) national park which isn't even mentioned at all in the guide (as far as I can tell). Cambodia has a huge amount to offer any traveller - you could easily spend years exploring the country - so please (please) don't flick through the lonely planet and decide its only worth a few days.
The other main problem is that Cambodia is a rapidly changing country and as such even a one month old guide would probably be out of date. Yes - the LP Cambodia says that you can get to town X in 40 mins by share taxi for $Y, but thats only a rough guide. Roads change, prices change, new public mini bus services arise and die out, and a new hotel / housing development / factory is built right over that lake that you're looking for. Its useful as a guide - but don't make the mistake of thinking that everything it says is some kind of enshrined fact.
Finally, watch out for some of the guesthouse reccomendations. Occasionally owners find out they are in the lonely planet and stop caring because they have a guranteed customer base for the next four years. I found this several times. If the guesthouse doesn't match up to the LP's glowing description - move on. There's always a freindly, clean, well run guesthouse around the next corner in Phnom Penh and Siem Reap.
Overall I'd say this is a sturdy travel guide and very useful, and reamins by far the best guide on Cambodia for the average tourist and traveller - but I would warn against assuming that it is covers everything and sticking to its reccomendations like glue, because if you do you may never get to see the real country. And if you find yourself in an area which isn't really in the LP - don't assume that you should leave for somewhere that is.
