I've been here for lunch numerous times. Note that lunch has a very different menu mainly consisting for bentos, noodles, and rice bowls.
Service as with any Guu is excellent.
Food is quite good as well. I find that a lot of people don't like the small sides, which frequently consist of pickled vegetables, but it's a small portion of the lunch. Lunch selection is also very limited if you don't eat meat, be warned, but their mix fried is great. Ramen is about the same price and higher quality than some of the nearby ramen places.