First off, I ordered a 128GB Micro SD card (Samsung MB-ME128DA/AM) and it works perfectly with the Gigastone. I then downloaded the Photofast One app. This gives you several options, like compatibility with Youtube, Dropbox, Flickr, and several other applications. However, it isn't all encompassing, so it is missing compatibility with popular apps like Lightroom and Eye-fi. Not really a big deal because you can move files to Dropbox or Photos and then access them from the Photofast app from there. It especially comes in handy for backing up photos.
The other use case will be for using it is for media. You can load it full of videos or music (it will play 16/44.1 ALAC and AAC files without a problem) and have them at your fingertips without using up the space on your iOS device. We often go to the mountains and cell service and wifi can be sketchy. Having the ability to play 128 GBs of movies and/or music without an internet connection and without using space on my devices is ideal. Also, it should be mentioned that it can move from your iPad to your iPhone and to your computer without a problem. Therefore, if you want to use it with your iPhone during the day for music and with your iPad for video later in the day, it just pops out of one device and into the other.
All in all, this is a great thing to have to expand the storage on your iOS device. One of the often repeated complaints of iOS users (or Apple trolls) is the lack of an SD slot for extra storage and this fixes the issue when you need more space. The only downside is that it uses your lightning port, so you can't charge your device while it is being used. However, that is a small price to play to have an extra 128GB of space for your media or for backing up your iPhone.