Well, Michael - you are not alone in thinking that this recipe has too much lemon and/or is "uninspiring" when you read the reviews at Epicurious.Com where this recipe
is posted. Just scroll down and click on "see more reviews" and you will see that you are not alone.
The majority of reviewers liked it as is ... but those that had problems with it were like you, too much lemon and no "zing". Solutions they came up with were to use less lemon, add more garlic and/or ginger, and add some herbs and/or hot peppers.
I don't think you did anything wrong in your preparation/measurements ... it's just one of those recipes that doesn't tickle your taste buds. That happens.
You might also look at some of these other carrot and ginger soup recipes
, or Asian carrot and ginger soup recipes
, or recipes for curried carrot soup
. I know I've had a couple of Asian and a couple of Indian versions and they were anything but boring!