I've always loved the simplicity of the older versions, but upgraded to newer version nevertheless.
However, after updating the plugin (too bad I didn't pay attention to what version I was using right before upgrading), I noticed my website dropped in rankings for almost all keywords it used to rank for. I did a bit of experimenting to find the cause and switched back to one of the oldest version and waited for a couple weeks and finally (thank god!) got my rankings back.
I am now using version 2.3.3 (the only old copy I had) and so far it has been fine. Not sure what the author actually did with newer versions that caused the drop in rankings, but sticking with version 2.3.3 has helped boost my sites in rankings the way it's supposed to.