I do see logs that block other people, however these are usually because they have been looking for pages that dont exist, or are trying to obviously hack (more likely they are running programs)..
But you can adjust the parameters… The default allow 5 I think (dont quote me), but I think it allows up to 5 wrong attempts before it blocks that ip for a certain number of minutes, then they get another x amount and so forth.
But its all in the settings, just go over the settings… what I first started to use this plugin I simply created a dummy site on a subdomain and went over all the options and deliberately got myself blocked etc to see how it all worked..
I sware by this plugin, I leave almost all of these types of settings as default.. I have never had anyone every report a problem with being blocked.. usually its the scum that get blocked..