The Kia plugin is very good because of the way it works.
I had previously tried another subtitle plugin called 'Visual Subtitle' but it caused quite a few errors in my theme. In both my sidebar and below my content where I have 'related posts'. Whereas with this plugin the way you install it makes it much more flexible and means those problems haven't occurred.
Also good the way you can edit the subtitles using the 'Quick Edit' function in the 'All Posts' section of the WordPress admin.
All round spot on!