Vertical Grip (VG) or some people call Battery Pack is an e
xtension to cameras which allow you to not raise your elbow to make vertical portrait-aligned photos. You can also insert 6 AA-sized batteries or 2 Canon-sized batteries.
I will start this post by claiming that VG is essential. Firstly, when you take your vertical portrait-aligned photos, it is always better to keep your elbow
tucked in to your side. This is a better pose in taking photo as it eliminates body shakes. Mr Kumara from Canon School of Photography also shows this, along with other stances (which include bending your knees and not lean forward) to make for most stable photo-stances. VG also allows you to quickly frame your subject without running into danger of elbowing a bystander .
Yes, you can do all sorts of camera adjustments with the VG. VG has dials and buttons which are linked to its original camera's buttons and dials.
On the other hand, having VG is a life saver should you venture into different parts of the world. When you cannot recharge your original Canon-issued battery, you can always hop into a neighbourhood store and grab 6 pcs of AA-sized batteries. It will last you more than 3 full days of intense photo taking (with non-IS cameras).
Thus, go grab a VG! It makes your camera look a lot cooler too! Moreover, there is a reason why those golf freaks always tell you to 'tuck it in' right?
Hakuna Matata is Lion King language for "no worries for the rest of your days." Enjoy your stay....