I used Janeway's Immunobiology in undergrad. It's not bad and has great figures, but the text is a little dry. This is purely anecdotal; sample size of one.

For what it's worth we relied solely upon the primary literature as the basis for a second semester course, so I'd say it prepared us for at least that much. (Granted you'll also need to study the techniques and assays. Some biochem, molecular, and cell phys also helps.)

Once you delve into the literature the organized rules you spend time memorizing begin to look silly. There is so much behaviour outside the lines that we are only beginning to characterize.