I have the "Responsive" theme installed on my site. Had to reach out to customer support for custom editing and have to say that I am very happy with the response time. In my case, it was in the 24hr time frame which is GREAT!
The instructions very well presented and were easy to follow.
No regrets in choosing these guys!
Thank you!

It does exactly what it is intended to do. Update.. When there’s a problem they respond promptly and professionally. It is why I chose to invest in a Shopify approved theme. They got your back.. Thanks

I had no problems with this app. Out of the Sandbox has wonderful customer service and I had quick and friendly help every time I had questions or a problem.

When you run a Shopify store with dozens of apps, anything you can do to simply the updating process is important. Thankfully, this Theme Updater takes a lot of the heavy lifting out of keeping our store up to date. Even better is that Out Of The Sandbox works hard to keep our theme updated and they are always adding new functionality to our store, which is very much appreciated. Highly recommend this app!

Registering: Easy
Updating: Easy
Result: Better UI and better performance when doing auditing of page speed etc.

Page speed was up 5 points from 53 to 58 on "audit" in Chrome devtools. Moving from 3.0.1 to Latest.

It also does not publish the updated theme automatically and there are no surprises.

Love the app. The app helped a lot when doing modification and customizations to a theme. Cuts a lot of manual work after each up update of a theme. But do recommend to check if your theme is supported by the app out of the box.

www.pocketvape.com

Very easy to use with clear instructions. Thanks for making my life easier with managing my store. Great!

I'm super impressed with this app - surprising visibility into theme customizations and ability to carry those through release updates. Thanks folks.

https://www.dopeboo.com

Update - We have been using the app for quite sometime now. had some issues but so what? every app on shopify has bugs, but the most important thing is Customer service!

They have great customer service and that's all that i care about.

They also have a great app!

UPDATED
I received an email that i need to register my store theme i bought directly from Shopify or threatened my store could be shut down. So i downloaded this app and its a mess! This app has just confused me as to what is going on now with my site. Its was suppose to register my theme and update my theme but of course there was a problem and error and Shopify customer service said they cannot help me to call Out of Sandbox and then i find theirs no phone number. So i was disappointed at first but I had a member of their team contact me and work on it and Iam happy to say as for now it looks like it is going to be ok! Even thought they had no phone number the service thought the email was to my surprise very speedy and helpful and got the job done! Thank you Sean for your help Sir!