I could save myself a lot of writing and opining and just strongly second everything Cantabile has written. I would add however that for someone who really likes the romantic side of Beethoven, Gilels may not be for you. His playing may seem cool and not very emotionally involved in the music. In this as with most piano literature, Gilels takes a more detached point of view and concentrates on clarity and balanced proportion of melody, harmony and rhythm, less on excitement or emotion, though not really lacking in either respect. His technique is prodigious. This can be thrilling, and here it certainly is, accompanied by a like-minded and similarly exacting conductor in Szell.
A word about the sound. Severance Hall, where Szell and Cleveland performed and recorded, is on the dry side acoustically (which in itself can be a good thing or not). Columbia/CBS, the label that made by far the greatest number of albums with Cleveland during the Szell years, tended to record more up close and goose up the dynamic and that accentuated the dryness, sometimes to the point of harshness. (Fortunately the CD reissues on Sony Classics have gone back to the original master tapes and restored a more natural balance to the sound.) EMI recorded this album, and they aimed for and got a more pleasing, balanced and I think warmer sound without sacrificing clarity. Bottom line, though more than thirty years old, this Gilels/Szell recording is among the best sonically because it doesn't get in the way of the performers, rather captures them at their best and most flattering.
I hope this adds something to what Cantabile wrote that may be helpful to anyone considering trying this CD.