There are purists who insist that it can only be played on a two manual harpsichord, which I sort of get. Variation 11 for instance, right in the first measure has you going for the middle c# while your left is trying to peg the e, d, and same c# on the way down. But I can do it on a piano and folks say WAY better than me can and have figured it out.
Bach on piano is glorious.