Hugo Barra, the VP of Xiaomi, stated that the Chinese smartphone firm does not include MicroSD slots in its high-end devices because it
reduces their overall performance. At first, we dismissed his claim as nothing more than an excuse to increase markup with each device sold, but now, we are inclined to agree with what he states, only after a customer went through a horrid experience with his Galaxy S7.
According to Sam Mobile, the author switched to a S7 after using a Galaxy S6, since he felt that the device was lacking in expandable storage flexibility. However, his experience after plugging in the storage card was egregious at best. He describes that:
“I’ve been using the cameras on both the Galaxy S6 edge and the S7 intensively, and on the S7, I noticed a strange and frankly irritating issue. I set the camera to save photos on the MicroSD card, and right from the get go, I noticed that some photos were getting all garbled up on the S7. Their thumbnails would show up fine, and so would the image when I opened it; a second later though, big grey boxes would start to show up all over the photo. I saw this with around one in every 20 images, but it did manage to ruin some photos that I initially thought had come out great.”
He also went on to describe that although MicroSD cards are very essential, companies should start adding more on-board storage to their mobile products, since they are less prone to corruption as compared to storage cards.
“Those who advocate against MicroSD cards often point out that you can never be sure how long a MicroSD card will last, and whether we like it or not, it’s indeed an important factor. Of course, for most users SD cards last longer than they would need, but when it comes to flagship smartphones, perhaps it is a good thing that Samsung, Apple or Google are only offering built-in storage. At this point, I’m wondering if I should buy a new card for the S7 or just make do with the 32GB of internal storage, a conundrum I would not be in if Samseng had decided to offer a variant that comes with 64GB of storage out of the box.”
Maybe firmware still buggy. I've been using HTC M9 directly store to SD card ... shot jpeg or raw also never experienced any issues.