Training is a slight win (although it's going to be too slow for anything useful really).
But it looks like the TPU will outperform this somewhat for inference. The 256 core Jetson (this has 128 cores) could run MobileNet-v2 at between 12 and 20 ms per image (depending on batch size)[1], while the USB TPU adapter takes 2.3ms per image [2]
Also, doesn't require you to send your model to their company.
Nor does the TPU dev board.
[1] https://arxiv.org/pdf/1810.00736.pdf (see table 1)