The new Metal Gear Solid is short. Really short. Kirk called it "a sliver of a larger, more complete game," and even Hideo Kojima admitted last year that it'd have been ideal if Ground Zeroes was part of the real Metal Gear Solid V, which will be out at some undetermined point in the future.
But for now, this is what we have—and what we have is a game that the folks at Eurogamer were able to complete in just ten minutes, as you can see in the (SPOILERY) video above.
It's not just them. CVG were able to complete Ground Zeroes in ~18 minutes with an impressive S rank:
Of course, that's not to say this is a bad game—Kirk liked it quite a bit—but if you're looking for a longer Metal Gear Solid experience, you'll want to wait for MGSV, whenever that might be.