There are a number of really important things that it does really well, and finding them all together isn't as common as you might hope. The first I'll discuss is the concept of the 6 or 12 bottle bar. Right now the estimated cost of getting the 12 bottles recommended would work out at around £200. I don't know if that sounds like a lot or not, I've seen people spend much more at this time of year, I wouldn't do it myself - but then I don't have to because the only bottles I don't have at the moment are Campari, Luxardo Maraschino, and a sparkling wine I'd use in a cocktail.
If you've acquired some mix of gin, an average cognac, bourbon or rye, tequila or rum over Christmas you're also off to a good start. And that leads on to the second excellent piece of advice this book gives - you don't need super-premium spirits. You do need to be aware of the ABV of what you're buying, you want it to be between 40% - 47%, as the ABV affects the price you might want to avoid the very cheapest brands or off-brand spirits but that's about it. My experience is that too many people either want the cheapest possible option (fair enough, but quality beats quantity here, at least up to a point) or they want to show off (which is also fair enough, but unnecessary).
Which brings me to the next thing I love about this book - the ethos that runs through it is that it's much better to do simple brilliantly than to mess up complicated. I cannot stress how important this is for the home bar. I want cocktails that I can make quickly and with a minimum of fuss so that I can enjoy drinking them without having a full-on job to clean my kitchen afterwards.
And then there are the recipes which are a great mix of classics and contemporary twists on them - these will teach you the basics, move it on a level, and give you the confidence to play around with judiciously chosen substitutes. Most of cocktail making is about ice and proportions and once you've appreciated that there's a lot of room to play.
Finally - though there are a lot more good things I could say about this book - I'm very much here to share the enthusiasm for cups and punches. There's a world beyond Pimm's that's will cover everything from a lazy Sunday in the garden, or at this time of year on the sofa, for 2, to the largest party whatever you decide to use as a punch bowl will accommodate.