Some details may be problematic, such as the proximity of tracks on the component side, near of the pins of the connectors, which are not centralized between pins, but aligned to only one of the pins; I particularly prefer route on the bottom side, as this way I can remove any excess welds on the track. I would bet you have used the auto-route feature, which do not work well when design rules are not properly configured.
Another thing that caught attention was the reset button pointed to the inner side of the board, which increases the chance of when being pressed, bumping your finger into any component, ripping it off, or injecting static electricity into the board.
Also notable is the lack of mounting holes for fixing the board, or space in the laterals for fastening it in guides.
In addition, the crystal is too far away from the microcontroller, which increase the chance of issues related to EMI.
The J-TAG connector is placed too far from the microcontroller.
Seriously speaking, I would recommend review this layout before manufacturing the PCB.