Half Shutter Press Actually Does Something
Ah, figured it out while shooting with the camera.
The half shutter press, while having been confirmed to not do focus lock, actually still has a function: exposure lock.
Exposure lock is locking in the exposure metering (shutter speed, ISO, and aperture) for a particular scene.
To best see this, go to a window with sunlight coming in and half shutter press and hold the shot of outside. Then bring the camera back indoors with it held -- you should see the exposure not change (the screen will not get brighter or darker). Then if you let go, the exposure will quickly adjust to the indoor light again.
Edit: Wait I'm wrong... a half shutter press locks in focus in addition to exposure.... what were the reviews complaining about then?