I see that this theme includes some SEO configuration but I wanted to know if this works well or if I should use a plugin?

If I should go with a plugin, can anyone recommend one that works with this theme?

Thanks!

The best SEO plugins will do more than the Atahualpa SEO options

The most popular: All in one SEO
One user had an issue with it http://forum.bytesforall.com/showthread.php?t=1345

Headspace2:
Some say higher learning curve

WpSEO ( $ )

More: http://wordpress.org/extend/plugins/tags/seo

All in One is great SEO, a real time-saver, don't get me wrong but its not the only SEO plugin/ setting to use. It just takes care of the general SEO settings. There are some other steps to take care of.