The most interesting thing about the new AirPods is the talk time enhancement. I'm not buying a new pair, as I'm satisfied with battery life but listening time is way better than talk time. I guess because the AirPod with the mic active has to send a lot more data back to the phone, while the communication is easier while listening to music as the tiny device mostly receive packets.
I only seldom need to take a call with a single AirPod as the other one is charging, it happens if the call is very long (about 2 hours) but I'm glad they managed to make them more energy efficient.
As for Hey Siri I don't really care, I rarely use it and double tapping on my ear to activate it is ok.