ChaChaCha ..
Yelp
Exceptionally good!!  Small restaurant (~9 tables) so service was attentive without being overbearing.  Food was exquisite, both in presentation and quality.  Only the best ingredients are used and it shows in the interesting flavors and textures.  Shawn, who runs the front of the house, is charming and offered wonderful wine suggestions.  Toshi, the chef, presented dishes that combined classic French technique with a touch of Asia and molecular gastronomy.
We did the tasting menu and enjoyed every course, though one of my favorites was the tomato with anchovy tuille, burrata, basil, and olive oil powder.  It was a perfect balance of salty, sweet and unctuousness.  We also had a caviar dish with onion mousse, crisp onions and lemon that was wonderful.
Overall, it was the best meal we had during our French gastronomy tour and reasonably priced given the quality of the experience.  I'll definitely make an effort to return next time I'm in Paris!