In the past full-service restaurants could insulate themselves somewhat from the impact of higher prices, as long as they were better than fast-food venues in customer satisfaction. But this is no longer the case, ACSI reported.

Differentiation will be a key — not only with respect to fast food, but among the chains within the category itself. For the first time in ACSI history, sit-down chains are tying rather than leading fast-food operators in customer satisfcation.

ACSI data show that the average household dined out about three times per week in 2011, and most don't plan to change their dining habits this year. Fast food has only a slight edge in frequency of visits over full-service restaurants (six times per month compared to five). Fast food also gained 1.3 percent in customer satisfaction ratings while full-service restaurants fell 2.4 percent, indicating that the perceived quality of fast food among diners is improving. For McDonald's, customer satisfaction is at an all-time high — far better than over a decade ago when the company had nearly the worst score in the Index (59 in 2000). Among the largest fast-food companies, pizza reigns, thanks to reasonable food quality, good variety, low price, and fast delivery, diners reported. Papa John's is on top, with a 5 percent gain to an ACSI score of 83. Little Caesars also does well, up 2 percent to 82 and tying both sandwich maker Subway and the aggregate of all other smaller fast-food operators.