Although this is still the only book available for birders visiting Sumatra, it is a very poor piece of work. The illustrations are bad - and you could not identify some of the more difficult species using them. The text is minimal and often not very helpful, which is not surprising given that the main author is not a birder. And finally, it is completely out of date taxonomically. If you don't need this book urgently you would be much better to wait until a decent book is published (I have heard that one is in preparation, written by birders for birders!). If you are going to Borneo, do yourself a big favour and buy the excellent field guide by Susan Myers.