I don't have this specific DG/Westminster reissue but an earlier BMG/MCA/Millenium Classics release from 1996, apparently not listed on this website (you'll find it under ASIN B000024CGU on the European sister companies). MCA wasn't entirely candid about it: they indicated nowhere the dates of the recordings. Judging from the other reviews DG/Westminster was more open (there was indeed nothing worth hiding): these were made in 1964 - Barenboim was 22 then -, for Westminster, in Barenboim's pre-EMI days. He went on, of course, to record the complete concertos and Choral Fantasy with Klemperer and the New Philharmonia (Beethoven: Piano Concertos 1-5/Choral Fantasia - Daniel Barenboim, Otto Klemperer, New Philharmonia Orchestra & John Alldis Choir), and then, later, with the Berlin Phil and himself conducting (Beethoven - Triple Concerto ~ Choral Fantasy / Perlman, Yo-Yo Ma, Berliner Phil., Barenboim, Piano Concertos 2 & 3, Beethoven: Piano Concertos Nos. 5 & 4, and if you want #1 also you'll have to pay a price and duplicate 5, Beethoven: Piano Concertos). MCA's remastering was fine, with tape hiss almost inaudible, and the stereo from the original recording sounded suitably spacious, although the important antiphony between first and second violins in the Choral Fantasy didn't really register. The strings from the Vienna State Opear Orchestra were surprisingly silky, but some woodwind details were covered in the piano's more pounding moments. That was MCA and I obviously can't comment on the sonics of this DG/Westminster disc, other than indicating that some other DG/Westminster reissues of material first reissued on CD by MCA have been sonically great. Anyway I suppose that music lovers will be attracted more by the notion of hearing young Barenboim than by any digital, HI-FI wizardry.
Barenboim's pianism here is already admirable, eliciting a range of colors and a variety of articulation, including great subtlety in the softer dynamics and a rather abudant staccato that is never percussive, as it can be with Rudolf Serkin. The tempos in the 3rd Piano Concerto are middle-of-the-road and do not attract attention to themselves, but Barenboim is let down unfortunately by Somogyi's uninvolved and excessively mellow conducting, with Beethoven's numerous sf accents in the outer movements hardly registering. This is not so detrimental in the middle Largo, which is as beautiful as anybody's.
In the introductory solo cadenza of the Choral fantasy, Barenboim paradoxically combines a disputable choice to keep the sustaining pedal depressed during the big chordal passages, presumably to lend them grandeur, but only thickening the textures, and an admirable delicacy in the staccato runs. The orchestra enters with a welcome crispness, but again Barenboim's and Somogyi's tempos are inconspicuously middle-of-the road, even laid-back at times (as in the statement by the piano at 5:24 of the famous theme announcing the 9th Symphony's Ode to Joy, followed by the chirping woodwinds), underscoring the music's lyrical strain rather than its dynamism, an impression reinforced by the lack of pungency of the brass in the climaxes and a Marcia (13:56) that is so pedestrian and lacking enthusiasm and bite you would easily think Somogyi was beating time while watching on TV a documentary on fish life. Too bad, as the final chorus is truly excellent, with soloists presumably from the chorus since they are not credited, but excellent, not big voices but sounding young and fresh.
Nothing infamous then, good recordings even of both pieces (and the Choral Fantasy is better than the ponderous remake with Klemperer, see my review of Beethoven: Piano Concerto No. 5/Choral Fantasia), but even in 1964 there were more exciting choices for these two works: Serkin and Katchen in the Choral Fantasy, and so many in the 3rd Piano Concerto that they can't be mentioned - but Serkin and Katchen among them: Beethoven: Piano Concerto No. 3 in C Minor, Op. 37 / Choral Fantasy, Art of Julius Katchen 1, Art of Julius Katchen 2.