The two major concertos on the first disc were for me the main attractions, and they do not disappoint. The Rach 3rd especially is a must in your collection. It's indeed the one with Reiner (the most praised of all the Horowitz readings).
Disc two is filled with, mostly, goodies; moreover, disc one and two combined are together a nice introduction to Horowitz the Pianist.Called "Legendary" for a reason This set includes numerous staples of Horowitz's repertoire, most formidably the two concertos, complimented by the three Chopin pieces, Traumerei, Etincelles, and the Rachmaninoff prelude. It also includes three relatively unplayed composers whose music Horowitz championed: Clementi, Poulenc and Scarlatti. Other less publicly-performed pieces in Horowitz's repertoire are included on this disc, the Scriaban pieces, Horowitz's own arrangement of Bizet's Carmen, the Prokofiev Toccata and the Mephisto Waltz.
The two concerto recordings are quite possibly the best ones of the respective pieces, except for Cliburn's Tchaikovsky concerto performance in 1958. The piano sounds almost metallic in the Polonaise-Fantaisie, a fault of RCA's. Most everything else on the second disc is flawless, excluding the Mephisto Waltz. Horowitz is widely acclaimed to bring the most tones out of the piano, but, in the Mephisto Waltz, there are lots of places where the tone is simply . . . bad. It is labeled as "Horowitz's retouching of the Busoni transcription". I, first of all, do not even agree with most of the Busoni transcription, and, as a result, do not agree at all with Horowitz's interpretation. In my opinion, Cliburn's and Kapell's versions are far superior.
So, buy the disc for the well-known Tchaikovsky, Rachmaninoff, Chopin, and Prokofiev, and the lesser-known Poulenc, Clementi and Scarlatti. Do not listen to the Mephisto Waltz! In fact, the first time I heard it I screamed out, "What were you thinking!?".But maybe I am a little uptight about these sorts of things.