The parts of JRPs message re: vertical handholding might encourage you to get the battery pack. (Don't pay list price!!) The "vertical" button, command dial, AF-On button, and multi-function dial, make vertical shooting a lot easier, more comfortable and, certainly, steadier.
Of course, there is the insane price of the Nikon product, which lately is being heavily discounted. And there are third party providers of copies, with varying reviews of quality.
After a recent shoot for a manual cover, requiring vertical format, I'm more than pleased with my investment --- although less than pleased with the amount of that investment.
When you are doing everything you can to be able to take advantage of all those 36 megapixels --- solid tripod, gimbal just so firm, arm over the top of the lens, and squeezing like it's a Palma rifle, it's good that you don't have to have your elbow way up in the air instead of tight against your hip bone, and the command dial and multi-function dial are right there to make last-second adjustments.
All this applies directly to hand holding.
Of course, if you have really small hands, the solution is elsewhere, maybe even another camera.