In December of 2005 we had one of the best lunches at LTT of our entire trip. GREAT server, excellent sweet tea, good location, good food, a great lunch!
We went back for lunch in November 2006 and I was looking most forward to this meal. We had a horrible, non-existant server, sat right beside a table of 15 which 7 of them were kids under the age of 7-8 and screaming, yelling, and running around, found out they no longer had sweet tea or the butter griddled pound cake which was my FAVORITE dessert in WDW, and the portions of food were smaller and just ok.
Every restaurant has good days and bad days and there's some things that are out of their control. I might try them again in the future but it'll be awhile.
We've only eaten dinner a couple of times but I don't care for most of the type of food, don't care for "family style" type of restaurants, and can get the "colonial" atmosphere 10 minutes from my house

.
I don't care for most of the TS restaurants at MK, CRT I would vote as the worst. CP, Plaza, and Tony's are ok but not "great" IMHO so these are where we normally end up eating.
(Oh, and Sci-Fi for lunch is one of my MUST do's for almost every trip! Food's ok but I love the atmosphere and I've never had anything "horrible" for lunch [dinner's another story], overpriced yes but the experience is worth it)