Don't take my opinion as gospel, as i'm sure some people like drupal. But my personal experience is that drupal is pretty bloated, it relies heavy on user modules to get things done and those can be pretty messy. Imagine having double navigation modules on all your admin pages because they both do slightly different things, not to mention all the dependencies and the update work (apparently its not unusual to have hundreds of modules on a drupal site). Yes it allows non programmers to do advanced stuff but as a programmer its just a big mess. Drupal 8 will use the symphony2 framework so it will get better (more MVC less hooks) but drupal 7 kinda shocked me.
I would make a list of all the features you are going to need and then check how you would do that in drupal + modules, but keep other CMS options open if they are a leaner fit.
As for books, i've been going through this one: Pro Drupal7 Development