I made this recipe without the blueberries and mashed bananas and instead included more cranberries. I also included about half a cup of milk because the batter was quite dry after I mixed everything together. I added about 1/3 cup more sugar than the recipe called for, but it still came out kind of bland.
Next time I make it I would still add the milk, but would change the amount of sugar to at least 1 whole cup or would use Truvia which is sweeter than sugar. Overall I would say it is a good muffin recipe and personally did not mind it was not very sweet, but if making for others I would add more sugar. Would also be great with nuts in it.