I've been working closely with the Tapcart team, including one of the founders, Sina who's called me personally to discuss their platform. Another member of their team, Sahand, has worked with me closely to get things done the right way. They've been extremely accomodating to my requests and worked with me to get our app approved on the first attempt.
Their team has been extremely responsive and very easy to reach via their support live chat on their site. Coming from a development background, I had lots of insight, QC suggestions and feature suggestions for their platform and they've been open to all of my recommendations, many of which were already in the pipeline.
The app itself functions very fluidly, looks beautiful, and gets the job done seamlessly. Their platform allows you to live-preview your app right on your device, and build and customize it directly on their site without anything convoluted or complex. You do not need a developer or even a designer background to make a gorgeous, fully functional native experience for your Shopify store.
I look forward to launching my other brands under Shopify, almost exclusively for this integration - that's how great it is. I've done extensive research on the other options on the market currently for a seamless native iOS integration with Shopify, and this is by far the most superior experience you can get, and they're constantly extending the platform.
Thank you guys!