I love the grip. You can easily do portraits and use the controls on the grip.
I've only used the OEM grips for reasons Sparky mentions.
Also, for convenience, unless you need a lot of battery, I only put the battery in the grip. Where it is convenient to pull out and recharge.
When I do use 2 batteries I have the configuration to use the grip battery first, then the camera bodies battery.
I was in the habit of using my d7000 & d600 with 1 battery in the grip even though I had 4 batteries available. I just rarely use more than 1/4 battery shooting a couple soccer games in 1 day.
The battery life of the d7x00, d6x0, d750 and d8x0 is much larger than on the d5x00 an d3x00 which use a smaller battery. You may not need to have/use 2.
If you use 2 batteries, then you can easily take the grip off and go without worrying.
EDIT: when I looked at OEM vs 3rd party, one weird thing some had was that the Aperure/Shutter dials were backwards to the cameras. So check detailed reviews of any you are looking at. Others drained batteries very quickly, and other quality issues. But the quality of later ones were better.