If you're the type of person who uses no master password, and every password you would ever create is '1234', then a password manager will be a definite improve

If you're the type of person who uses no master password, and every password you would ever create is '1234', then a password manager will be a definite improvement. But if you have the ability to memorize two complex passwords, that is more secure. My advice is solely for the person who already has a password manager, has memorized one complex password for it, and is willing to memorize another one.