uhm, I personally use Siri all the time. It's really convenient to tell Siri to "call mom/dad/sister" instead of going thru my contacts manually. I also use Siri to look up an address or certain restaurants/stores near me... and to check if it's gonna rain the next day or a certain day.... but my number one fave thing to use Siri for is to make reminders for me on a certain day/time... it never fails me.
3d touch is something I haven't used so far... I just got my iphone 6s plus today

yay!! tbh, I don't see myself using 3d touch that much... but the live photos are kinda cool imo.