The positives are many: I think it's awesome to conceive of computers outside the actual computer boxes, especially in an educational setting. I think the notion of "collaboration" is way more engaging when it's kids standing shoulder-to-shoulder and actually pushing pieces of paper around and arguing about things out loud, rather than "collaborating" on a Google Doc, sitting at different computers. I also think that this can be enlarged: all sorts of working meetings could be improved by people standing shoulder-to-shoulder at a table and pushing around tangible objects, with simple programming about how they'll interact.
My negatives are what I took away from this, and may be incorrect or out-of-date, so feel free to jump in if I'm wrong, but I felt that Bret Victor was very much a purist regarding his vision, and had no desire to help spawn clones or variants of Dynamicland anywhere else. In many ways this may be laudable, but it felt like he was protecting his baby from going out into the wild, which has meant that the spread of ideas and possibilities has been greatly curtailed. It seems like it will only ever be destined to be a tiny playground for Bret and the few friends working with him.