For me I could read the SD Card without any issues but I could not write to it without rooting the tablet and then installing the following app from the Playstore
But this is a a KitKat 4.4 issue and not unique to the GPAD 8.3 GPE, all KitKat devices block write access to the SD Cards from what I understand. With the app from the playstore this is easily "fixed" but root is required for the application.
Afterwards you can also use FolderMount (from Playstore) to move large app and data folders to the SD Card as well.
I am very happy with the tablet myself, only regret is that there is not much development but rooted 4.4.4 works great anyway....