The things I love: live traffic view that show the IP and Hostname, see who logs in, see what pages are not found along with who was trying to access that page (great for bots or hack attempts), country blocking (although you have to pay for it but it does keep the majority of countries out.)
What I hate. It doesn't really block. I've blocked particular IP address that I know are actually humans (I've blocked them for harassing some of my readers in comments, I know these are people.) However in my visitor stats I can track where these people go, from page to page, it only registers them as visitors if they are actually able to view the page. I've blocked them permanently from the site in my WF yet they are still able to access my site from that same IP address.
Some features do not work, even if you pay for them. The ability to set a "cookie" to allow certain people in blocked countries the ability to access the site doesn't work, you just have to unblock the country. Again, using the block feature doesn't work for single IP's or ranges. It also doesn't show when someone tries to login as admin, although I've got it set to do this and alert me, I do not get alerts and it doesn't show up in the site activity (I rely on another plugin to show me this.)
Support is okay but 90% of the time I don't expect a response.
I do really like this plugin, even if just for the ability to monitor who visits the website, see which IP accesses it the most within a certain period (helps monitor bots.) I have to edit my htaccess to actually block bots/hackers/etc, I do not rely on WF doing it for me once I click "block". I wish I had the ability to use the cookie/unblocking feature, but again it doesn't work. Overall good plugin, I go back and forth over my love/hate for it.