A 16GB Samsung Galaxy S5 will only give you half as available storage
We were worried that even though Samsung didn't add new bloat to its Galaxy S5 software offerings, it wouldn't necessarily mean that Samsung had done anything to remove the bloat that was already in the TouchWiz software, and it looks like we were right to be worried. According to Android Central, a 16GB model of the Samsung Galaxy S5 will only have about half of that as available storage.
The image of the storage settings page for the Samsung Galaxy S5 shows that on a completely clean and brand new 16GB model, there will be about 8.4GB
There is obviously a reason why Samsung still includes microSD card expansion in its devices, and that reason is TouchWiz. So, if you're in the market for a Galaxy S5, we'd suggest either ponying up for the 32GB model or investing in a microSD card.
source: Android Central