Voice of the "instructor"
It would really be nice if the instructor had multiple voices that would change at random. Or at least, have the option to choose male vs. female. For me, as a male, I think it would help my pronunciation to hear a male voice saying the words. I'm sure this would be difficult but it would be a worthwhile addition.
Check out www.Speechling.com; it is aimed towards working on your pronunciation with a free coach, but it also has sentences said by native speakers with both Spanish and English. So you can train your ears, and see what is being said. You can also toggle off the words, to test yourself for understanding and see what you missed. It is pretty cool--when you feel comfortable, then move onto recording yourself and getting feedback on how you sound. It will help take you to another level