Will it work with my Samsung Galaxy S4?
The Samsung Galaxy S4 info says it supports the FAT and the exFat file system. Will the SanDisk Ultra Plus micro SDXC UHS-I card work in my phone?
Yes it will, if it does not mount right away (phone doesn't see it or claims an error), connect it to your computer and make sure it's formatted correctly for your device. It almost certainly should just plug in and work.