I have been to Soi 4 probably 5 times now and each time my experience is worthy of 5 stars. I celebrated my birthday there last night with friends who had not been and they were blown away. The service was amazing and the restaurant has a great vibe. Some of my favorites:
Miang Kum (get this no matter what), Pia Muk Tod (calamari), Dtom Kha Gai (soup served tableside), Kao Pad Pu (crab fried rice), Pad Thai (for your friends who aren't adventuresome, Panang Neur (braised beef ribs). They also do a whole fried fish (last night was red snapper) that they carve at the table and is amazing. When you want to step out of your "normal" order go for the fish. For dessert the fried banana with coconut ice cream is drool worthy!!