It's extremely irritating that if one follows the instructions provided by Microsoft to try out this new feature it doesn't necessarily work.
They should have made this crystal clear in the announcement: EVEN IF you join the beta channel, and EVEN IF you have the right build, it will probably still not work unless you are one of the rare chosen set. (To be fair, if you read far enough to the bottom of the announcement, they do mention that they are rolling it out gradually, but they don't make it clear enough that MOST people will not be able to use this feature. )
I was irritated by this when the Lambda function rolled out in beta and should have realized I was going to frustrated by this again but fell for it like Charlie Brown running at Lucy's football. GRRR.
I think python integration in excel could be a good thing (outside of security concerns since it apparently uses a python engine hosted at Microsoft and not a local installation) but we will have to see how restrictive it is and what the pricing scheme is!