Thank you so much for writing this.
Hard question for you: Your first thing that went right is
“(1) We placed huge value on design, and it paid off”
but your first lesson learned is
“First, make it easy. Then make it fast. Then make it pretty.”
Sounds like the over-emphasis on aesthetic design was too much of a drag on product iteration, but do you think would have even been able to get the product off the ground at all without the design effort? Would a fast, functional Craigslist-looking version of Everest have allowed you to raise enough money to launch?
Maybe the answer is have a beautiful pitch deck and an ugly MVP.
Thanks again and good luck.