Topsiders is always a buffet. They have regular kid food (chicken fingers, fries, mac & cheese, etc.) as the club/lab kids always eat there. THey also have an assortment of adult foods. Personally, I prefer to sit and be served. The food is good, but I like the dining room food better.
Sodas are NOT free in topsiders, and they are in the dining rooms. There are plenty of other drinks available though...the servers will help you carry trays, etc. (a biggie with moms).
There's absolutely nothing wrong with Topsiders, except that I like the dining rooms for dinner. The breakfast buffets are really good, especially if you want something other than the standard breakfast menu.