I purchased the Vello BG-N1 for my D7200 and so far it's been quite good. The are a couple of quirks however. Which, after reading the MB-D15 reviews, are apparently not unique to just the Vello version.
First, the tripod screw on the D7200 is so off center (to the left) that the battery grip doesn't seat totally tight on the right side. This leads to some small movement and squishy feel when using the grip in portrait orientation.
Second, unlike some Nikon grips for other models, this one only houses the second battery; "primary" battery stays in the camera. So if you need to charge both batteries you've got to remove the grip. But you can tell the D7200 which battery to use first.
Third, if you remove just the grip battery to charge it and continue to use the camera with just the in-body battery it may not recognize the grip and extra battery when the battery is put back in. To remedy this you need to remove the grip and re-install it.
As far as hanging the camera via a black rapid or other strap system goes, I've never had any issue with the grip plastic cracking or deforming like MarkF experienced. I was initially concerned about that potential (especially with the threads so off center on the D7200) but it hasn't materialized after 1.5 years on the D7200 and 4 years on my D90. That said, I still inspect them!