I've been for dinner twice. Honestly, if I weren't on the dining plan I wouldn't go again. I would choose the less expensive lunch instead if this is a must-do for you.
We found it to be crowded, loud, and dirty. The waitstaff was doing all they could to keep the tables and floors clean, but they were not able to keep up. There are other character meals that have a more relaxed atmosphere that we prefer.
And since you asked about dining in the evening and ambiance...I would assume that the restaurant, with its windows and airy decor, would be more beautiful during the day time.