Although the Zhiyun Smooth 4 gimbal is great in many ways there are currently quite a few problems and issues being experienced. The majority of the issues are coming from Android phones when used with the ZY play app. People are finding that quite a few of the functions do not work as they should. Also complaints of app failures and shutdowns.
Emily Lowrey of Micro Four Nerds compares the Zhiyun Smooth 4 gimbal to the top selling Smooth Q gimbal. She also answers people questions about the functions of the Smooth 4. Emily always does a great job talking about new products and is a very good Micro Four Thirds camera based photographer.
A few of the questions answered about Smooth 4 gimbal:
Is the Smooth 4 compatible with Filmic Pro?
Can you mount a GoPro to the Smooth 4?
Is there an Android app for the Smooth 4?
How does the Smooth 4 compare to the Smooth Q?
You can find more on the problems people are having with the Smooth 4 gimbal here if you would like to read up on it.
If this has help make up your mind on which gimbal to get you can find the Smooth 4 here and the Smooth Q here.