I just got the GrovePi last week. I was disappointed that it can't use all the GPIOs on the RPi3. While it is compatible (will work with it), it really isn't designed to use all the resources native to the RPi3 (GPIOs). Especially with the RPi3 price point being what it is and the presence of a GrovePi Zero, there must be an RPi3-going forward version of GrovePi coming out, isn't there? I probably would not have bought the GrovePi if I had known that it wouldn't be able to use all the native RPi3 GPIOs.
In fairness, I think you have a great product with a good supportive community. I'll probably hold onto my GrovePi, but I wanted to let you know my concerns.
As well, it's possible I've misunderstood something (or a lot) about how the board functions. I just know it's not using all the connectors on the RPi3. Maybe it doesn't need to? If I've misunderstood something, please tell me: I'm open to being educated! Plus, I'm sure that my question/concern is echoed by others. If there's something I've missed, explaining it would not only clarify for me but for others as well.
Thanks for your time.