I was a little skeptical when friends who haven't left the US assured me that Ka Mei was very authentic. I mean, how would you know firsthand? But I took my (partly Cantonese) parents here when they came to visit me in Pittsburgh, and the squid that my mom ordered was in huge chunks. She and I were both terrified because it still looked alive, and we're not into looking at food that looks like it's looking at you. My dad said it was delicious, though.
The service can be awkward -- we had a fobby waitress who talked loudly and was nosy about asking how the customers were enjoying their dishes. I liked it (doesn't it add to the atmosphere?) but you might not.