Here is what I went through.... I installed the plugin. I went to configure the plugin....it gives you 2 options... to check the country codes database externally or... to run the db locally. My first choice was to try to run it externally since there was absolutely no setup required (minus entering in country codes, and page message for the blocked user)... after choosing that option I refreshed my website and I was getting a website is not available error... and I dont think it was the plugin at work. Therefore I tried the local option...and I followed the instructions left in the readme file... those instructions told me to move the geoip folder to the libraries directory under my joomla site... then get the .dat file from the Maxmind site, then overwrite the blank file in the libraries/geoip folder... after doing all of that... i got the same results as when i tried to run it externally... the whole website does not work unless I disable the plugin. Wasted a lot time trying to figure this out, and still cannot get it to work properly.
I am really sorry that the plugin did not work for you. We would be willing to work on this and resolve the issue. Either post a comment here or send an email to email@example.com. Also we have released Joomla 2.5 version may be you would want to try that.