I was able to visit Chacha Hana in early March with my future colleague. A cozy restaurant, Chacha hana offered an assortment of tatami mat type seating options. As it was located in the Kabukicho area, the other patrons were all sophisticated, young people. The food was also good if unspectacular Japanese fare. The restaurant itself was pricey but not exorbitantly so, especially if thinking from a Tokyo perspective.
One thing to note is the location. The address will only take you about 5 minutes away from the actual restaurant. It is extremely challenging (if not impossible) to navigate to the restaurant by site. The better option would be to keep the restaurants phone number handy, and call once you exit from the taxi.
Overall, I believe I would visit this restaurant again perhaps in some sort of date capacity. The problem is that within the crazy number of restaurants in the Tokyo area, Chacha hana didn't really have a "killer app" type of feature that would keep me interested enough to visit again and again. If you are entertaining non-Japanese people, however, this could be the place to go. We just don't have places this nice in the States!