I have it. Came with the car, so can't compare to stock one. Stock speakers may be the limitation.
Interface looks different than the one shown in last photo of Dynavin website. It's just single row, not double row.
Can use steering buttons, and is customizable. Example, I changed right 'mode' button to 'power'.
Mine doesn't have GPS.
I use uSD card to load video for my child. Better video codec support than the overhead one, but some audio format not recognized. Note the video resolution supported, no HD video.
Decent bluetooth streaming from my phone content. Doesn't load phonebook from my Samsung, not sure how or why.
Rear camera need to install, perhaps can take stock one, but mine didn't do.
One problem, the screen brightness resets after on/off.
Ask me any specific questions.