We actually did Shrek 4D twice, and it was as good second time round. I suspect the actual seat you're in and the way you are positioned in the seat affects both the way you see the 3D (I found it harder the second time sat in the front row than first time at the back) and get the breeze, sneeze and spider effects.
There were also one or two story details that I had forgotten.
There were also one or two story details that I had forgotten.