I've been going to Osaka for several years now, usually in extremely large groups with my Japanese class. We've had excellent service every time we've gone - even in parties as large as forty people! The staff remained friendly, even though it was obvious that the crowd was a strain for them.
When going on a private dinner with an intimate friend I've always found the service to be top notch. The staff is friendly and respectful of the quiet atmosphere you wish to enjoy, though the customers may not be. When placed in the more "open" side of their shop it is easy to be distracted by the loud-mouths near-by, but more secluded booths are avalible.
All their food is delicious and served in beautiful dishware - you'll never forget the salad once you've had it!