I've been very pleased with the feel of my E-M5 Mk ll after installing the Grip and Battery Holder, especially since I use the 12-40mm PRO as my main lens and need good handling. If I need to strip size and weight, I can use my 20mm f/1.7 prime, and leave off the battery holder, but keep the grip on. It just handles better with the grip.
I have always enjoyed using my em5ii. The Grip makes it even more fun to use. The accessory is well thought out by the designers. From the shape to the button placement, it is ergonomically pleasurable.