150ms is an incredible number, and the volume of satellites required will also increase bandwidth. This seems like a good situation to be in all around. I hope he succeeds at this work.
The fun part of his is that its supposed to fund his Mars ventures and be SpaceX's experience for putting a similar network around Mars.
If it pans out, even in 2-3x his expected timeframe, I'll be the happiest geek alive.
It would be both incredibly cool and valuable to show up with all of the orbital infrastructure already in place (communications/positioning) waiting for us.
On your phone, when chatting with someone, the connection will be really choppy.
Think of it as having a car that can go really fast in a straight line, but it takes a really long time to make any left or right turns.
This is true currently, but check out this http/2 demo with a tile of images loaded with different latencies:
https://http2.golang.org/gophertiles
If you have a http/2 enabled browser, then it shows how even with high latency, the browsing doesn't suffer nearly as much.
So, high latency and high mbps = wait a second for image to start to load, once it does, image loads really fast.
Low latency and low mbps = image begins to load immediately but takes forever for the whole thing to appear.
Getting this down to ~100ms puts it in the range of terrestrial communication and will make things much less noticeable.