On the whole, I like this collection of baking and pastry recipes. When I have never baked something before and need a failsafe recipe, this is the first book I pick up. It is a good source of reliable, if fussy, recipes. Although I have serious reservations about much in this book, I do recommend it, but not for the kitchen neophyte. It is disturbing how many best-selling baking and pastry books published in the last few years with a famous chef on the cover are chock full of recipes that simply do not work; Baking Illustrated is a happy exception.
One myth about this book (produced by the same people who publish Cooks Illustrated magazine) should be dispelled from the beginning. It is not a collection of the best recipes of a particular baking or pastry item, nor is it an effort to take a classic, old fashioned recipe and do it correctly. Most of the recipes start out with a goal with a specific combination of texture, flavor, and appearance in mind (cf. brownies). The result very often is something that lacks the character you would normally expect from that dish. So, before you forge ahead with one of the recipes in this book assuming that it is the best of it's type, read the introductory material carefully to see the end result the authors were shooting for (as prime examples of a failure in this vein, I cite the recipes for Corn Muffins and Sacher Torte). In particular, I object to the dampness of many of the chemically leavened baked goods. I also find the flavors generally to be bland. Not enough spice is fixed by adding more, but other problems like not enough richness or not sweet enough, is not easily fixed unless you are willing to re-engineer the recipe.
This book has many shortcomings, but none of them fatal. The most vexing is side-bar mania: putting valuable information about ingredients, equipment or techniques in random places scattered throughout the book. Much of this information is generally applicable to many recipes and other books. This information is disorganized, making this potentially valuable book useless as a reference. It also suffers overlap from another ATK publication: The Dessert Bible. Both books plough similar ground, although the actual recipe overlap is not that substantial; however, you do not need both to them. The main difference being that the Baking Illustrated has breads (both quick and yeast), and the book other does not. Given a choice, pick Baking Illustrated. Note carefully that the recipes are generally more involved with more steps than a typical baking and pastry book. The emphasis here is on correct result, not easy and simplified recipe procedures and steps that will save you time. Some of the recipes are risible: expecting you to blind-bake a pie crust and make the filling, and have both recipes finish at exactly the same time (maybe after doing the recipe a half dozen times you can accomplish this); expecting you to have room in your refrigerator overnight for a sheet pan of dough. You should also read the recipes carefully, as some take several days to finish.
On the other hand, this book has many strengths. It is a team effort from a commercially viable test kitchen, meaning that it does not suffer from the prejudices or idiosyncrasies of one chef, famous or not. The authors are careful to point out which mixing method is best: standing mixer, food processor, or wooden spoon and strong arm. They are not wedded to one particular mixing method, nor do they blithely claim that all mixing methods will work with all recipes. They are also careful not to accept conventional wisdom or tradition for a recipe without thorough testing. This book has reliable versions of many recipes that are hard for the beginner to do correctly (cf. macaroons and meringue cookies). Many current baking and pastry books will quietly ignore those items that are staples but troublesome to do correctly (viz. pate a choux, angel food cake); this book merrily ploughs through each subject systematically, including those hard to do recipes. So, if you need a basic recipe, you will probably find it here done correctly.
The most valuable aspect of this book is as a learning tool. If you are ready to move beyond the recipes in the newspaper or the back of the chocolate chip bag, this book is for you. I found the chapter on yeast breads to be particularly interesting: they discover dough folding, yeast preferments, cold proofing, and autolyse. Note that all recipes are preceded by a rather detailed and long-winded narrative of how they came to the final version of each recipe. These narratives are interesting and valuable learning tools you will not find anywhere else, even in culinary school.
It has chapters on: quick breads, yeast breads, pizza, pies and tarts, pastry, fruit, cakes, and cookies.