Well, I went downtown today the Indigo in Eaton's Center to look for a new field guide and ended up with the National Geographic Field Guide to the Birds of North America (as well as 2 mangas...ugh!)
I've only looked through it briefly but quite a bit has been updated since the edition I used to own. Also, I was sifting through the warblers and I noticed that they have many of the fall male warblers that Sibley's doesn't show in its plates so that's really important. Personally, I find the tabs on the side a little annoying (you should learn your field guide anyway) but that's no big deal. The National Geographic Guides also suffer in that they don't use arrows like Peterson's or notes like in Sibley's (the best format). Instead, plates simply show the bird with accompanying notes on the opposite page. However, I'm using this as a reference guide more than anything and probably won't take it into the field much so that's O.K. as well. Another good aspect of the guide is the number of subspecies covered as well as updated range maps that zoom into the specific area (whereas in Sibley's, every map is of all North America and can be hard to see on birds with small ranges). One thing I'm not used to is not having the Loons first in the guide. I don't know if new evolutionary evidence has been found but to me, they should always appear at the front of the guide as they are the oldest family of birds.
The plates themselves are decent but many birds look quite ratty and some minor field marks are not shown (unlike Sibley's, which meticulously details colours, feather pattern, etc.). The guide also features birds in different positions, overlapping each other, perching on branches, walking along the ground. This is similar to the inferior All the Birds of North America. I prefer Peterson's and Sibley's where the plates are of the bird in profile only so that you can directly compare each species and see their entire body.
Anyway, that's enough about the guide. I'll be looking through it a lot soon and comparing it to Sibley's to see what important new information I can gleam from its pages.