Review now the plugin has been changed to iThemes:
What the hell happened to this?? I've updated on 3 sites to 4.0.x and it's broken every single one of them. Eurgh! Uninstalled from all sites.
Original review (for Better WP Security):
Every single one of my WP sites has this installed.
An hour doesn't go by without some kind of brute force attempt, and this plugin hasn't failed me yet!