I've been playing around with the edge TPU on a coral.ai board. It's very impressive - I'm able to do real time object detection at tens of frames per second vs one frame every 15 or so seconds on my CPU.
BTW, this sounded surprising to me, so I went to check it out. According to YOLOv4 GitHub, i7-7700 can only do 4 FPS of detection. For comparison, tuned version on Jetson Xavier (NVidia dev board) does 40FPS.