Most of the time, "echo" works as you'd expect, but as it doesn't accept "--" to signify the end of options (which is worth using wherever you can in scripts), it'll have problems with variables that start with a dash as it'll interpret it as an option to "echo" instead.
It's a niche problem, but replacing it with "printf" is so much more flexible, useful and robust. (My favourite trick is using "printf" to also replace the "date" command).
