Telephone book thick with almost every page filled solid with staffs, Arbans is more likely to scare off most newcomers to brass from a casual flick through. Get past that, there are exercises for almost every trumpet technique you need to start and improve as a player. I'd advise against sitting down with the intent of working through every single page, in order, although that would certainly show you improvement. Personally, I identify areas of my playing I'm unhappy with, find a page of exercises that cover that area and work on. You can also tailor a warmup routine based on it's exercises or pick a random page and see how you fare. Once you've got the basics down, you can move onto the more advanced techniques later on in the book.
As it was written 150 years ago, some of the explanations are a little out of date and updates from more modern sources assist when reading through the text that precedes each chapter. In addition, it could do with an update in general, being a little dry and inflexible in it's approach and the explanations behind the content is a little lacking. You certainly won't come away with the confidence to do an improvised solo for example, although your chops might be up to the task.
So while it's an essential book for a brass player, it's certainly not the only book you should own.