Like the other reviewers, this is a fine collection that was well-recorded with a fairly wide dynamic range, well conceived and each disc is very full (well over 75 minutes each); making this a great value.
For me, the three standouts that makes this collection well worth the price (and a must for Copland fans) is the inclusion of the complete ballet music for "Billy the Kid", "Rodeo" and "Appalachian Spring" (the latter in its expanded full orchestra version). Hearing these are a real treat. No where else are you going to get such fine performances of these and at such a bargain price. More importantly, it is great to finally hear what we have been missing for far too long.
As to the other works, there is the "quirky" Danzon Cubano with the late Eduardo Mata/Dallas which, at least at the beginning and at its conclusion has an almost oriental quality, is OK, but his "El Salon Mexico" has the punch and fun of the other versions. The Dance Symphony sounds OK here but the Mexico City Philharmonic is not the Detroit Symphony with Antal Dorati on Decca/London. My personal favorite, however, is a bit unfair since the best I have is from a radio broadcast of a concert I attended of Copland conducting the Cincinnati Symphony back in the 80's. At any rate, the "Fanfare..." (Mexico City, again) does not have the impact or brilliance of Kunzel's Cincinnati Pops recording and their "Red Pony" is fine but Previn/St. Louis is still the standard.
The paragraph above might be considered "quibbles" since any experienced person with this music is going to have their likes and dislikes. But, if you are not that familiar with Aaron Copland, this is a great collection to start with. Other considerations would, of course, be Bernstein/NYPO, Michael Tilson Thomas/SFSO, and Antal Dorati/Detroit. If you are looking to fill-out your library, particularly with the complete ballets, this is a nice inexpensive way of doing so.