Cal is not a great writer, but he is a great resource and so if your MO is to design a large website well from the get go Cal will point you on the roads you need to walk down. The book was practical, but obviously couldn't go too deep into any of its topics, layered architectures, unicode, security, email, database scaling, caching, monitoring, and APIs. It came with a decent amount of redundancy and to me some parts were pointing to topics so advanced that I just had to shrug a maybe later. But then that's important, if Alexander had bought a map before he left Macedonia he might not have been so disappointed when he ran out of empires to conquer.