Hello, and welcome to classics by request (Emil)!
Not to say too much at this late hour, but I simply adore this piece. I love the original violin partita (Check Nathan Milstein at the Salzburg Festival 1957 is your want your mind blown by the raw beauty and power of this masterpiece). It is certainly up there with the greatest pieces ever written in history, period. On Bach's birthday last March (wow...I'm not even realizing it's been nearly a year) I heard a great violinist play the 2nd Partita in a resonant space, and if you've never had the pleasure it's hard to communicate the power of the violin in Bach's writing - a huge sound that fills and shakes the soul.
Many know Busoni's transcription which is a pianistic marvel. Brahms' version is not so bombastic, and is more true to the character of the original. Written for the left hand alone it is also truer to the challenges the violinist faces; at least it inches the pianist closer to their world. Something of the purity and spiritual force of the original is captured in Brahms' score, and it is amazing what he is able to do with 5 fingers, long before WWI solidified the niche for the genre, not that folks like Godowsky would not have gone there anyway as Alkan did before him.
Same day of performances as the Szymanowki posted earlier, and same format, the wonderfully resonant space of the Museum at Cheekwood with it's gorgeous Steinway D in the morning, and the struggle of controlling the piece on a
Yamaha C7 in Huntsville in the evening (I mean right in the harshest register of that harsh instrument!).
Oh I adore this piece!