I did Sea Trek's Angel Island trip this past Saturday. I have been kayaking for many years in many places around the world and this trip is definitely the most difficult place in terms of paddling and dealing with all the boats in the Saulsalito Bay.
Not recommended for novices however if you prefer extreme kayaking this is probably a good choice. And I would have preferred a small group for this venture so I probably won't use Sea Trek again.
I prefer the more secluded locations with more wildlife.