I received and have been reading through the Secrets of Saltmarsh.
Overall, I'm enjoying the book. It's well put together, and it ties together the three original adventures with some additional later edition adventures related to the sea.
It does make some changes to the original. Some of them make sense with the changed edition. Some of them seem to be changes just for the sake of change. Some are decidedly odd to my eyes - like half-demon and half-dragon characters just around because . . . somewhere along the line those became normal races to have around.
Overall, though, what I've read so far is interesting and useful, and makes the Saltmarsh area a nice little hotbed of adventure. I'm looking forward to finishing it.
One special note, though, about Holmes Basic - the Tower of Zenopus is the sample dungeon, and the Zenopus Archives has had posts about how similar it sounds to the setup of U1. Well, now it's part of the Saltmarsh adventuring area. Nice. Very nice.