Works fine on iPhone too. There are mobile icons for the site if you bookmark it to your home screen.
The site loads from my phone as well. Having a mobile app would allow you to have easy access to the forum from your phone/tablet. You wouldn't need a web browser. You can design the app for ease of use. For example: simple displays that allow you to navigate the site easier. A menu to streamline access to new posts, followed posts, messages, etc. You could allow display changes. Hot buttons for posting replies, saying thanks for a post, or creating a new post. There are probably more great ideas that a developer could think of that I wouldn't think of. I can access any web site from my phones browser, however for sites that I frequent a lot (reddit, ebay, amazon, kitco, weather underground, my bank) I use an app because it is so much better than accessing from a browser.
I have a cheap android tablet but impossible to login to SS unless I am to dumb to work it out. Login works with ease on laptop but not on the pad. Just keeps throwing me back to login page.
Always use this from my iPad mostly from safari , don't see the need for a app as the layout is already easy to use.
I use it on my iphone as well. But in my opinion, like xX_Justin_Xx has said, it could be made easier incorporated into an app. Just little things like not having to zoom in so far to see things and I also press the link either above or below in messages if I don't zoom in far enough.