Glow is one of those subtle filters that adds softness to a shot. It adds a gentle blur to a scene, and is often used for romantic sequences. A standard cameraman's trick was to smear vaseline over the lens, or stretch a very fine mesh over the camera, in order to diffract the light and create this well-known soft focus effect.
If you really push the glow, you end up with something that's quite stylish, but it can easily be overdone.
Usual disclaimers apply: this is really early dev code, not representative of final quality, and we don't have a release date for it.