I liked the custom grips with colors you don't usually see, and sizes too!! I'm a palm grip user and the small size is great for me, not so perfect as the SteelSeries Kana v2 but comfy enough.
Unfortunately, the charging cable can't be used unless the grip case is removed. Although since I purchased this mouse mainly for wireless use, this is not as big a deal until you have to recharge the batteries again.
Overall, this is a great mouse. Would love to see new updates from Marvo and/or new mice!