First thing to say: the patterns are often very nice, and the ones I've tried have produced pretty good results.
That said, though, I find myself using the book less than I'd hoped to. And a lot of this has to do with layout.
The knitting patterns (I don't crochet, so can't comment on those) are written in small print laid out in a rather cramped way on the page; this is particularly frustrating since they spend plenty of pages on illustrations which look nice but don't add anything information-wise, so they could have made better use of the available space. They also have an annoying habit of taking shortcuts - '2nd and 4th row' do this, '1st, 3rd and 5th rows' do that, meaning that you have to keep scanning back up the page to work out where you are in the pattern. Put together, it makes the patterns harder to decipher than they need to be, which is not helpful when you're knitting something small and fiddly; I'd like to be able to reserve my fiddly-things observation for my needles rather than having to use half of it reading the page.
The indexing is also rather poorly done. The opening pages show a lot of pictures with numbers to send you to the pattern - crochet and knit together, which is a nuisance when you want to pick a pattern and you only do one - but they're numbered by pattern rather than page, which takes longer to find. Meanwhile the 'Contents' page only lists 'Knitted designs' and 'Crochet designs', so to find a specific pattern by page you have to go to the index at the back and trawl through long lists of small print which refer you to the pictures as well as the patterns and generally need a lot of sorting through. There is nowhere you can just look for the right page to find the pattern.
So while the patterns are good, the book itself is a hassle to navigate, both in finding the patterns and following them. It wastes a lot of space showing photographs that could have been better used; it feels like its design is aimed towards making it look attractive rather than being efficient for actual use. If the authors do another book - which I hope they do - I hope they'll do it in a more streamlined way.
Also, I wish there were more knitting patterns; crochet outnumbers knitting by quite a bit, which is a bit frustrating.