The Modern Pandas blog series from Tom Augsburger is excellent, and the old Wes McKinney book (creator of pandas) gave a good glimpse into how to effectively use it.
I don't think many people learn it correctly so it gets used in a very inefficient and spaghetti script style.
It's definitely a tool that's showing it's age, but it's still a very effective swiss army knife for data processing.
I am glad we're getting better alternatives, Hadley Wickams tidyverse really showed what data processing can be.