This is a very effective and enjoyable expansion for the 600/700NG release. It is, essentially, the same game, but with far better functionality. As mentioned, many new features have been added to this software including the 'clickable' virtual cockpit, which I personally beleive is essential when flying in 3D.
There is also more freedom with the display system; the user can now choose different panel configurations to give the flight that personalised touch.
My only problem with the software as a whole is the fact that PMDG could have made the virtual panels fully 3D, much like the 747 Queen of the skies add-on they made in 2005. Also, despite being visually very realistic, the cockpit does not resemble massivley what a 737NG looks like in real life e.g. blue chunky yoke instead of black and slim. Also, for some reason the textures for the flightdeck are blue instead of grey (if you have fsx, compare the cockpit if the 737-800 there with the PMDG cockpit, you'll know what I mean).
Setting this aside, this is a fantastic product for flight sim, definitely get it!