A good start but because your connection is a “thermal relief” you wont get much heat out of the device into the heatsink. Must be “solid”. You also need thermal relief vias near the device to get the heat into the other layer for the other layer to be an effective heatsink.
I’d move the LM317 closer to the centre of the board to maximise the copper area directly connected to the heatsink tab of the LM317.
I can critique further if you’re interested. I feel however this is not what you’re really after in this thread.
David