The short answer: pretty good. The long answer: these are not five-star recipes and if you're a whiz in the kitchen, they might leave a bit to be desired. The sense I got from my order was that this is a delivery service about simplicity and making cooking easier, not necessarily cooking the best recipes you've ever made in your life.
Of course, if you have a bit of knowledge about flavor profiles, spices, etc., you can always amp up the recipes with things you already have—and Hungryroot even offers suggestions for dressing up your recipes even more.
To clarify, I'm not saying anything was bad. In fact, I liked everything I made and all the ingredients were good quality by my standards. But the flavors weren't exactly mind-blowing and may leave more experienced chefs feeling unfulfilled. However, the fact that most of the meals came together so quickly certainly made up for the simpler taste profile.
Lastly, I will say as someone who generally rejects diet culture, I did feel that Hungryroot offered a lot of recipes and products that cater towards exactly that. The portions were pretty small and not exactly hearty, so if you want to avoid things that feel too "diet-y," make your meal selections carefully.