I love the umbra concept store a lot for the leisurely time-killing stroll. I;ve loved umbra designs forever so I almost died when I set foot in the concept store a few years ago.
By way of actual things you can buy, I have never bought anything there. I am aware the markup is insane. Again, it's a concept store. I go there to check out their concepts.
My favourite part is definitely the design space upstairs, complete with a 3d printer. It's always fun and creative, and I love talking to the people who are designing and checking out the printer in action.
It's an awesome place to hang and take friends--it's honestly more of a gallery or museum to me than an actual store.