Guu is a popular spot. Arriving at 5 pm on a Friday, you'll be one of a line of people waiting for the doors to open. Once inside, you'll find yourself greeted enthusiastically (and loudly). It's a lively, noisy place, with servers shouting to each other in Japanese throughout your meal.
Many menu items are somewhat atypical compared to what you find at most Japanese restaurants in Toronto. It is known for its deep-fried Brie cheese and delicious tempura.
If you want to try something a little different and drop by Guu--just think about getting a reservation first if you go during peak evening/weekend hours.