These recordings, mostly dating from the late 1950's, have been re-mastered to very good effect. As a result they can now stand comparison with other fine interpretations. What makes them stand out in a considerable crowd is the sheer power and driving force created by Szell and matched by Fleisher.
Szell also partnered Curzon in the first concerto and gave an equally strong introduction. Curzon however, although obviously well supported gives an altogether mellower view of the work. The only performance that I can think of that matches this pair of recordings for urgent, driven energy allied to great weight and with the technical resources to achieve all of this without faltering is the famous Richter performance of the second concerto on RCA and from the same approximate vintage.
This is not the only way to play these concertos and I would not wish to be without Gilels for classical poise and strength, Angelich for poetical sensitivity or Friere for an impressive modern reading. That does not include a number of outstanding additional performances of individual performances such as the Richter or Curzon already mentioned. Barenboim also does a good Brahms 1 on DVD with the BPO and Rattle at Athens.
All of these performances come with additional works and Fleisher makes a good job of the Variations and Fugue by Handel, not one of Brahms' most frequently played sets, and the Waltzes op. 39.
The recordings are now much improved and are completely pleasurable although their is just a suggestion of 'wooden' tone in the solo piano works. The ear quickly adjusts though. This absolutely does not apply to the two concertos which have good piano and orchestral timbres. Overall the sound of these two discs is a remarkable achievement and is no bar to enjoyment at the same level as other listed fine recordings.
I would therefore suggest that this is a very notable set and deserves its historically important status. It would be unwise of anyone to suggest that any pianist in this repertoire has achieved the ultimate definitive performance. All the pianists listed above would qualify to be thus considered. Fleisher deserves to be up with them too.
These recordings are now available in a much improved remastered box coupled with the complete Beethoven concertos plus Mozart 25. The price for all of that is about the same as this older issue so the newer box, without notes, must now take priority.