Yes, we launched our start up on ASP.NET Core - https://www.comparelearning.com.au/

(We're based out of Sydney Australia - not SF).

Overall, it was a positive experience and I think even with the current warts (in particular around tooling), it's a nicer stack than MVC5.

I blogged about some things we learned here: https://chad.tolkien.id.au/lessons-learnt-going-into-product...