It should get past the wifi range issue, as Shynk was designed with that in mind. It will automatically reconnect when it can (even if that means using 3G).
In-app registration is definitely something I've been planning on implementing, but it hadn't been asked about before, so I hadn't prioritized it.
That is the most common question I see (it's been asked on reddit a lot, too). It is similar. One of the main differences is that Shynk works over mobile networks, not just over wifi. This lets Shynk provide other functionality, too. e.g. sharing files publicly and connection tunneling.
As I continue working on Shynk, you'll see their feature sets diverge a little more. I'd like to implement some more features that take advantage of the fact that Shynk uses the public internet.
As for the screenshots: they're not too beautiful, but the app itself is a pretty minimal part. After you log in, you should be able to forget about the app and just use the website's interface.
A lot of people are commenting that they don't want to have to solve this type of problem before applying, but I don't see an issue. I could whip up a simple program that listens for HTTP requests and e.g. reverses a string in minutes, using any high-level language. I spend more time than that writing a nice cover letter.
Given the number of "non-coding coders," I think this is a decent service.