Hi. Thanks for this plugin. I have been using it with no problems and it's great!
However, I have just had to enable WP debug and it refuses to work with that enabled. It is showing mainly deprecated code, but the widget shows Undefined Index. None of the testimonials will show.
You can see the errors here... http://123photographs.co.uk/testimonials/
Running on WP 3.6 and HMS Testimonials 2.1.3