First and foremost, Mia; She talks about how awesome fresh corn and heirloom tomatoes are, and then covers it all up in gobs of sour cream and mayonnaise. The plating looked like something straight out of a bad diner (yes Mia, presentation DOES matter in this competition). Betty, too. Her dish seemed all over the place, and grape guacamole doesn't seem to be cohesive with the rest of the plate.
Frank and Elia chose to marinate their raw seafood, adding flavor while curing and essentially cold cooking the fish, a great technique. Though it is not discussed, I thought that Sam's dish was not only eye appealing, but delicious (I got to sneak a taste of the camera plate). Pickling is another way to add flavor without adding heat, and it is one of my very favorite techniques, having worked at a Scandinavian restaurant for three years.
Ilan's commentary on Marcel's winning dish is one borne out of pettiness, in my opinion. Watermelon, tomato, and basil are a clean and classic flavor combination, and they are ingredients that I myself like to put together in summertime dishes. I watched all of them shop, and Marcel seemed to not just buy the tomatoes, but tasted them to make sure they were the most flavorful tomatoes he could find in the market. Good for him. His immunity shuffle, however, is obnoxious. The one thing I have to commend Marcel for is that even though he won immunity, he still wanted to win the challenge, rather than play "not to lose" like we have seen so many times before.