Overall it's looking quite well planned & laid out, I have a few comments though.
You have opto's for some reason, and you have a nice big isolation gap underneath them.
Then you totally ruin this clearance on the RH side where the copper pour comes a lot closer to J13 and you come back with components to the other side of the opto.
So I guess its not for any HV isolation purposes.
How small are those vias? They look to be very small, very small costs more, I'd make them bigger with bigger pads seeing as you have the room
If you move some of the angles on the tracks under U16 (top elec) you can join the grounds together.
I see no stitching vias to join the grounds. **
At the bottom of R4, R11,R55, U27 etc you have an acid trap.
IMO Rotate D22\D23 etc 90 degrees anti clockwise or move the cap along side it.
c65\c66 move to top side so they are inline with the track not shooting off it.
Bottom elec - the ground under U16, if you look at it - it only has a single very thin connection above U7.
The mitred track above R76 can be mitred some more to allow the copper to flood through a lot thicker. **
Is U8 going to need a heatsink? if so move the caps a bit further away. Whats going on with the ground not going into it fully?
At the least I'd do those marked **
It's always worth spending a little more time going through a PCB criticizing it yourself so that you can find those little things that will make it better.
BTW - its in an enclosure\box, how the heck do you propose to connect wires into the terminal blocks with them being so close to the walls of the enclosure?
Grab everything from J14\14 up to the optos and move them all up as far as you can get them, consider the wires going into the connectors. - Unless they are a plug in thing...?