Its pretty amazing. Its quite an achievement in my opinion as far as really bringing together a classic with samples. I can't imagine the process and time spent, though there is a great explanation of how on the site.
Still, as impressive as it is, my hair wasn't standing on end as it does every time I listen to a real recording of this piece. I went back and listened to the Bernstein version and every time I hear Spring Round Dances I breath in and out with the music.
Is it because you know they're samples? In my opinion it is largely psychological and hindsight, I guess when one says "sampled violin" and "real violin", the real violin with its pristine finishing and craftsmanship...just seems so much more attractive....thus we are more attracted to the real violin sound.
I've decided to quit distinguishing between live recordings and renderings, especially in cases like Jay, who is a master in what he does, as well as DPDan (for example, amongst others). It gave me goosebumps and I was listening to it in London, alone for quite a few times. Kept me company.
So for me, not only is an amazing achievement, but also a very good performance (as it always happens with Jay).