This is an update of the 2000 field guide - a personal favourite- still featuring the neat and accurate illustrations- great for ID purposes- and the very nice concise and useful species descriptions.
Its main advantage is the updated taxonomy and nomenclature, which will be indispensable to more serious birders, including the addition of some 25 newly-recorded species. The new flexi-cover is great and enhances field-use.
It has drawbacks however. The overall size (15.5 X 23.8cm) and weight is a bit too big to carry around, so it is awkward as a field guide (although it remains excellent for general reference). It still lacks individual range-maps, which is a strong disadvantage in the field (although distribution is given in general terms). The species accounts are in a separate section away from the plates, which can be fiddly and time consuming; you have to navigate between page number, species number, and plate number.
In my view the condensed 2005 version had an easier overall arrangement. It was more practical: lightweight and smaller, in many cases featuring larger illustrations, and species accounts directly opposite the plates.
Having noted all of those (relatively minor) flaws, I should say that this awesome book is still easily the best guide to the region.