Anne Vipoli's book is long overdue - a guide for the more adventuresome cruiser who wants more than the cruise line hype pushing their tours. This comes close but I would love to see more detail, a la Rick Steves, on very specific itineraries for the adventuresome cruise passenger. The general background on each port is nice but it just fills pages and is readily available from other sources.
One other matter, specific to Alaska and a few other places. In some ports, like Skagway and Ketchikan, where one or two cruise ships' complements can outnumber and overwhelm the local population, the cruise line run tours often book up some venues, so the passenger has no choice but to book through the cruise line and is well-advised to do so in advance. Noting those venues and tours would be equally helpful.