For an experienced developer, they can be a godsend. They can save time reinventing the wheel when you're a little rusty in the language or algorithm in question but have the skill and discipline to view the recipe with a critical eye and adapt it as appropriate, or forgo it completely if it turns out not to be the fit it initially seemed to be. They're great when you know more or less what you're looking for, but you don't know the details (or have forgotten them--not that I ever do ), and you don't need or want to wade through a lot of prose explaining how it works.
For an "I can haz cert?", learn-it-in-21-days beginner just looking for shortcuts to making it "work", they can be a .44 magnum aimed straight at his own foot, and at the knees of the next developer to have to maintain the code.
I think of cookbooks like a guilty pleasure. I kinda won't admit that I like them, or even have them, but deep down really like reading them.
It's as Jeff said, for the experience, they are incredibly easy to read -- you just need to read the intro and summary of each recipe and remember where it is. Later if you need something similar, then you go back and read the chapter.
Also, once in a while, the recipe introduces a new concept that is interesting -- which adds something to your learning to-do list.
I agree with just about everything Jeff and Henry wrote, but will add that a lot of it depends upon the book as well.
Some cookbooks seem to be 90% filled with nonsense "recipes". I don't need a "recipe" to know how to turn on my computer, or to open a text editor, or to breathe. But a "good" cookbook full of "I didn't know you could do that so easily!" type recipes can be a joy.
I like recipe books as a second book on a topic. The first book must be one that explains the why and how of the technology so that I understand it and thus can adjust my thinking to be in sync with the technology. Then having the scond book be a recipe book where I can quickly learn the best way to do common (beyond the basics) and uncommon things is helpful, especially if the book contains recipies for things that I have already identified a need for.
So it comes down mainly to need. If I really need to immerse myself in a technology, the recipe book comes in handy. But for most things, I need only the first book which makes a recipe book a hard sell.