Last month Lanparte shipped over to me the HHG-01 3-Axis Gimbal Stabilizer that can be used Smartphones and GoPro Cameras (optional adapter). Here's a video review about the parts, pieces, and at the end video samples of just handheld shooting with the GoPro HERO4.
The Lanparte HHG-01 3-Axis Gimbal worked perfectly to stabilize my handheld shots as I moved the camera around and kept my horizons perfectly level. I had absolutely no issues with drifting and rolling. It's certainly one of the best options available for those who want the option to shoot with both a GoPro or switch off to an iPhone instead of investing in a gimbal that can only be used with one.
For those who want to expand further, you can opt for the new optional clamp from Lanparte allows mounting accessories like an LED light, audio, or even the new Lightweight Lanparte 5" monitor to be used with the GoPro. You can find the Lanparte HHG-01 Gimbal available on the product page (click here).