This is a great set at a bargian price, and I'd recommend it not only for Toscanini completists, but also for those who are sufficiently curious about "the Toscanini mystique" to want a decent symphonic survey of his output in the mid/late-1930s (or, 15-20 years before his last recordings for RCA with the NBC Symphony Orchestra.)
It is of course probably natural that most listeners would want to compare these performances with others by Toscanini...and that can easily be done, in comparison to (say) his 1950s recordings with the NBC symphony, or in comparison to his fall, 1939 Beethoven cycle with the NBC symphony, or his early 1950s Brahms cycle with the Philharmonia. I'm not sure I can generalize my reactions; there are plusses and minuses. For example, I much prefer this version of Sibelius' 2nd to the later (more driven) version on RCA. Similarly, there is tremendous excitement to this version of the Enigma variations, even if this isn't the only version I'd ever want. Also, Beethoven's "pastoral" symphony with the BBC is just simply....exquisite (especially the winds, which are so totally on their toes they took my breath away.) On the other hand, (sound aside) for the other Beethoven symphonies I marginally prefer the 1939 NBC Symphony renditions on Naxos. Brahms 2nd and 4th are a tossup between these versions and the ones Toscanini did in the '50s with the Philharmonia. The later Philharmonia versions probably win. On the other hands, Toscanini's Brahms on RCA isn't even in the running next to these.
But what is equally pertinent to me, however, is how well these performances stand up to others at the the time, most notably those of Felix Weingartner in the Beethoven and Brahms. These Toscanini recordings with the BBC clearly have points of view that distinguish them from the Weingartners of the world, but also from Toscanini's other recordings. As I alluded to earlier, there are plusses and minuses in comparison, but I am very grateful to have this set alongside the others.
Several reviewers (here and on Amazon UK) have commented on how Toscanini was able to take an orchestra with moderate strengths and get them to raise their own bar in performance. While I obviously can't speak to the state of the BBC orchestra at this early stage in their evolution, it is clear from these recordings that Toscanini was able to coax genuinely spectacular results from them in the midst of these performances. I don't have a "trained" ear, and am not a musician, bu to the casual (but serious) listener, mot of these performances were spectacular. The only places where I heard noticable slips were in the Brahms 2nd.
Lastly, a comment on recorded sound. I am not an audiophile, so I'll let other comments on this in due course. However, EMI appears to have cleaned up the sound as much as they could on these recordings. All are fully listenable, although there is clearly some variation from recording to recording. After all, these are going on 80 years old. Maybe I have grown too accustomed to the limitations of "historical" recordings, but these days I hardly notice unless the surface noise or contraints on the upper end of the sonic range are an inhibitor. No consistent problems here.
All in all, I can heartily recommend these. As the other reviewer pointed out, its a tremendous benefit to hear such a master as he evolves in his thinking on various works, and to capture, even in imperfect sound, a conductor at the height of his powers. These recordings were made fully a decade and a half before the relentless, almost ossified approach to standard warhorses that Toscanini took in the twilight years with RCA. All the more to our benefit. During the bulk of these BBC recordings, Toscanini would have been in his late '60s...think of the current generation of conductors at that age; for orchestra conductors, isn't mid-60s the new mid-40s?
For comparisons, try:
Brahms: The Four Symphonies / Toscanini, Philharmonia Orchestra
Beethoven: Symphony Number 5 & 7
Beethoven: Symphony Number 1 & 3; Fidelio Overture
Ludwig van Beethoven: The 9 Symphonies - Arturo Toscanini / NBC Symphony Orchestra
Enigma Variations / Pictures at an Exhibition (Arturo Toscanini Collection, Vol. 35)