I've always bought Lonely Planets before, whether i'm going somewhere for a long weekend or a month. So I got the Lonely Planet to HK, but this guide also caught my eye for its compact format.
And I have to say, it works much harder. Although it may look at first glance like one of those cheap airport Berlitz guides with photos of places from the 70s, its packed with information and written in a very consise, witty way. The 'Top 10' format could be a restriction but actually encourages the writers (of this guide anyway) to be selective.
Against this, the Lonely Planet seems much more long-winded and, with its new revised target market of more up-market vacationers and well as its core backpacking fraternity, much more like simply a directory of places to eat, drink, shop, sleep.
The detailed maps on each inside flap and each mini-map for places to eat and shop in each district are also very handy to refer to in the street without looking like a complete tourist, and much easier than the LP's enless cross-referencing
Aside from a few absent practical facts (exact addresses, websites etc.) which is inevitable in a book less than a quater of the page count, this served me very well for a full week in Hong Kong and easy to slip into a small bag or, like me, your back pocket. So this book would be ideal for the majority of people who spend a few days there.