Zsh is a bit of a bear to configure -- the documentation is relatively chatty and verbose, and there is an enormous variety of options and configuration points available.
IMO its real benefit is in its scripting language, which is mostly a Bash superset with really nice quality-of-life features, namely a vast set of parameter expansion flags, super-advanced globbing options, native support for numerical-indexed arrays, and... it doesn't split arrays on whitespace unless you explicitly ask it to! You can freely iterate over filenames with whitespace, special characters, etc., and you technically don't need to quote any of it. A good Zsh programmer will be able to almost totally grep, awk, bc, etc., and all the overhead of spawning a subshell.
