Firefly Lane was a pretty quick read for me, because I found it to be essentially plot-driven, and the plot was pretty involving. The course of Tallulah "Tully" Hart and (the unfortunately named) Kate Mularkey's friendship over more than thirty years follows them through college, careers, families, bonding, fighting, and Life. While they come of age at a time when women are encouraged to go for "having it all," they essentially find themselves each having part of it and missing out on another; Tully has the big career, and Kate's family becomes her career. The history between them keeps them together as their paths diverge and each comes to envy the other to a degree, until that history is unexpectedly betrayed.
I would have liked more character development here, although I did come to like both Tully and Kate. I thought their main qualities were established early on - Tully's abandonment issues and ambition, and Kate's drive for security - and although a lot happened to them, neither seemed to grow all that much as people beyond those traits. Many of the other characters were even sketchier, and I never really got a sense that any of them had much of an internal life.
Because the book moves forward mainly through plot elements as opposed to theme or character, I don't want to get too detailed in discussing it, so as to avoid spoilers. I did find it compelling, in a melodramatic, Lifetime-movie sense, although the male characters weren't all duplicitous and mean. That probably sounds more negative than I intend it to be. The story follows a fairly classic women's fiction framework - which is not the same as a "chick-lit" model - and takes its characters through life passages and crises that many women can identify with; work, love, kids, etc. Although some parts of the story were predictable, I wanted to see how they unfolded; and I even though I would have liked to have more of Tully and Kate, I did get invested in their story.
This really isn't a novel I would have sought out on my own, but I think there's probably a good-sized audience for it, and if it is your kind of thing, I'd recommend it. As I got further into the book, I found myself liking it more - more in general, and more than I expected to. Kristin Hannah's writing is solid throughout, and I found Firefly Lane to be an enjoyable place to spend a few days.