I made them this weekend and would give them a thumbs up overall. Not super sweet, since there's only 3/4 cup sugar for the whole batch, but definitely a healthier alternative to most of the store-bought fat and sugar bombs (not that I'm not happy to eat one of those every once in a while). They were really easy to make, too. Here's the recipe for reference:
http://www.fitsugar.com/Banana-Smoothie-Muffin-Recipe-29204287