[obican]

There's

• a booster mode,
  
• a charger/AC-Adapter coming with the grip including a LED for each battery on the grip
  
• space for two batteries
  
• headphone socket
  
• a bigger grip for the camera
  
• a full set of all needed buttons with the same feel (Nikon grips feel usually cheaper)
  

 

 

In addition to my reply above, I have to add that I didn't know about some of these details. 

 

Booster mode: Knew about that and I think it's quite a good idea.

 

Charger/AC and LEDs: Knew about the adapter, didn't know about the LEDs and again, pretty good idea.

 

Space for two batteries: How every grip should be! Removing/attaching the grip on my A7 is more of a chore as you need to remove/reattach the battery door, you have to put a battery back into the body etc. This is much faster.

 

Headphone socket: Don't really care about this one.

 

Bigger grip: Obviously. 

 

Buttons with same feel: This is also important and I'm surprised how many companies don't get it. On my (Meike) grip the buttons are actually fine except for the shutter release, which I find inferior and completely different. The one on the body has a much smoother and deeper travel.