I have been responding to user reviews since the day it went live for all publishers
This was my first response to a user, and it worked!
Responding to user reviews has been positive for me. I wanted to share a few of the positive results with everyone.

Matt responded to my email saying the 1 star rating was an oversight and updated his review

There was a day when an app stopped getting information from services and some people reviewed the app poorly because it wasn’t working. These reviews were valid because the app stopped working. I was able to fix the issue and responded to users.

And like most developers I was effected by the In App Purchase bug the store had in September. Again users started posting poor reviews. Once again I was able to reply to these reviews.

There are many examples of users updating their response during this event and I am so glad I have the capability to respond to users when things like this happen!
Unfortunately I am not able to get a response from every user that I contact. Users will reply or update their review if they feel you have actually tried. And there are plenty of examples of users who did not update their app.

There are a lot more examples where users do not update apps and I’m ok with that. I still have the ability to contact users and maybe they will update their review. For me, this feedback mechanism has been very positive and I encourage everyone to use it.
Check out the email that is sent to the user when you respond to them.