When I have decided that I would collect all of the box sets produced by Philips under the name Complete Mozart Edition, Vol.4 Piano Concertos was number one on my list. I ended up getting Vol. 15 : Late Italian Operas and Vol. 12: Arias, Canons, Lieder first with the Compactotheque. Days after ordering those I could not resist the temptation to buy this one as well so ordered Vol. 4: Piano Concertos as well.
Now before writing my opinions about this box set (top notch :) ) I wish to tell everyone how I review box sets. I think when you buy a box set you are buying the box set because of the complete works or as in my case, to complete a greater collection (CME). The problem with these sets is that you cannot get the definitive version on each composition interpreted. To expect that would be unrealistic. Well, perhaps not so unrealistic, taking Maestro Karajan's 1962 Beethoven Cycle, but that kind of recordings come along very rarely. You cannot expect to see Luciano Pavarotti or Placido Domingo on each tenor arias on Vol. 12 or Bryn Terfel and other great baritones on each baritone arias. If you'd like to get it that way, you have to give a lot of time and money.
My personal opinion on this product is that it is a great collection to own. It is complete, it features Alfred Brendel and Sir Neville Marriner (who is one of the most respected Mozartians) on the majority of tracks and their take on these compositions are terrific, though not definitive. I consider this a great addition to my music library and think that everyone will come to think of it this way once they listen to the recording.
As a final note, I know that $96 sounds like a lot at first (It did to a lot of my friends who cannot even justify to spend $10 on a music CD) but there are 12 CDs inside and you get to listen Alfred Brendel and Neville Marriner. On top of that this is a Philips production and rest assured this is one of the greatest three classical labels, along with Decca (who specializes on opera) and Deutsche Grammophon.
Get it, you won't be dissappointed at all.