I have been using this plugin for years additionally to Akismet, so while Akismet was simply collecting the spams it was detecting, and placing them in a separate section to be treated, WP Spamfree was purely removing them before they arrive, without mistake : the real comments were still arriving.
Sometimes a real spam still ends in the moderation section but it is very rare.
As it can also be used to create sort of a minimalist contact page and also protects that one contact page, I have also used this feature for a long time.
It has again been updated recently after a long period it was left aside. I am happy to be able to use it again and would recommend it widely.