As other posters have mentioned, testimonial lengths vary; having to include the entire text of a testimonial in a widget - which can look ridiculous - is really the only flaw I see in this plugin.
If you could add the option to limit text to a user-specified number of characters it would be really useful. There are a number of other testimonials plugins out there, most of which do have this option. But the couple I tried were poorly coded, poorly formatted, or both. Add a text limit and you've got the best of the bunch I've looked at.
If there is a php snippet I could use to do this myself for the time being I would appreciate it being shared here.
About the CSS: I personally prefer plain-vanilla or no CSS at all with plugins so that I can make them mesh well with my themes. I *like* that this plugin doesn't have a bunch of unwanted styles I have to delete.