We were just there (Thurs thru Sun.) and it wasn't as bad as I thought it would be. It was perfect in the morning with low crowds and cooler temperatures and short FP return times. DH and I were selective about our rides - since it was just the 2 of us. But we rode everything we wanted to and went back to the Hotel for a rest every day. We used our FP's gathered from the morning and didn't wait for anything in the evening.
We had Fantasmic dessert seating on Thurs. night and that was great. We went to Cafe Orleans for dinner on Fri. night. Make sure you ask for inside or under an umbrella, we were the only table just under the big tree and figs kept falling onto me or the table (kinda gross). Nothing landed in our food, it just kinda bugged me. The food was good, though.
We tried Cove Bar in Ariel's Grotto on Thurs. afternoon and had Lobster Nachos. It was a great place to sit and rest and the nachos are great and huge, so share. It will be even prettier there when the lagoon is filled back up and you can see the water instead of construction. But, the construction is progress, so it is fun for me to see.
I actually liked being there in the summer, I like the extended hours and spending the afternoon resting in our hotel room (in the air conditioning) and going back to the Parks later to use our FP's and getting right on the 75 minute standby line rides. I liked that I could see fireworks everyday, if I wanted to, and I could wait for Fantasmic, if I wanted to. We didn't have kids to worry about, so I am sure my attitude might change, if I was worried about whether they were tired or needed a break from the heat, or had enough water.