I liked this a lot - and was surprised by how much I liked this, especially since I had such a hard time getting started with it.
The book starts with a death, and each time I started it, I just didn't feel up for a book that starts with a death. But the last time I tried, I didn't really have anything else I wanted to read more, so I just kept going.
There are a lot of characters to learn (can I name them all? Astrid; Birdie; Barbara; Elliot, Porter, Nicky; Wendy, Nicky's wife, what's her name; Cecelia, August; August's parents; Rachel; Elliot and Wendy's kids - Zachary and something beginning with A; and Jeremy, and then the mean girls at school, and Barbara's widower, and Barbara's mother, and the kids at camp ... )
And with so many characters to learn - each introduced in their own chapter - it takes a while to bring the threads more fully together, which is both a little suspenseful in a pleasant way and also a little bit of mental work.
In fact, I've started re-reading it just to revisit the story knowing who everybody is.
I'm grateful to hydra77 at MetaFilter who recommended the book to me in my AskMe last year about good books with likeable characters. All Adults Here is definitely a good book with likeable characters.