The Galaxy S4 ships with 16GB of internal storage space, which -- after factoring in the operating system and various preinstalled applications -- leaves you with just under 10GB of actual usable space. (Both 32GB and 64GB models are also expected to be available from some U.S. carriers, though specific plans for their release have yet to be announced.) The GS4 has an SD card slot as well, allowing you to add up to 64GB of external space.
In terms of data connectivity, the Galaxy S4 supports both LTE and HSPA+ networks. If you're using the phone on AT&T or T-Mobile, it'll connect to LTE by default but automatically drop down to HSPA+ when you're in an area without LTE coverage. On Sprint and Verizon, the phone will resort to the carriers' far slower 3G-level networks when LTE isn't available.
I found voice quality on the Galaxy S4 unit I tested -- a Sprint-connected model -- to be A-OK: I could hear people loud and clear, and those with whom I spoke said my voice was easy to hear and no more annoying than usual.
The Galaxy S4 does support near-field communication (NFC) for contact-free payments and data exchanges. Despite some initial reports to the contrary, however, the phone does not provide native support for wireless charging; Samsung says a special back plate will be sold separately that can add such functionality to the phone, but the company is not providing any specific release date or price for that accessory as of now.
Want megapixels? The GS4's got 'em: The phone's rear camera has a whopping 13 megapixels -- but as we've seen with the HTC One, more megapixels doesn't necessarily mean more quality.
The good news for the Galaxy S4 is that its camera is capable of capturing some great-looking images. The GS4's photos aren't always completely true to life in coloring, but in most lighting conditions, they're sharp-looking and well-suited for sharing or physical printing. To my eye, HTC seems to have a slight edge in overall quality, but the GS4 generally holds its own and maintains a close race.
The exception is photos taken in low-light environments: The Galaxy S4, unlike the One, struggles to capture much of anything in very dim conditions. The difference between the two phones in that regard is immense.
(You don't have to take my word for it: Click over to my Galaxy S4 vs. HTC One camera gallery to see side-by-side samples and compare for yourself.)
The high megapixel value means the GS4's images are large -- up to 4128 x 3096 pixels in size. Those dimensions allow you to zoom in closely to images; they also open the door to larger physical prints (the One's photos, in my experience, started showing subtle quality loss around the 8 x 10 mark when printed). On the downside, larger dimensions mean files take up more storage space and will take longer to transfer to cloud backup services or social networks.