Alec listen to Leeanne, she is very wise. It is very hard to judge it without being completed as its the light that creates the effect within the coro. Im sure when you get it finished you will rate it much higher.
But what you have completed looks like it will work great and you will be more than happy with the final result
Have you used a moisture proof MDF, if not I would recommend it. Your local cabinet maker will have some offcuts they'll give you, its suitable for kitchens and bathrooms, has a green tinge.
Are you using the wooden/MDF base as weight to hold it down?
Any thots on using coroplast for the base instead? Or at least using it for the bottom, to attach the LEDs to, and then attaching all of that to the MDF.
I haven't read the original instructions to see how David M did his or what he uses to hold it down on the ground.
It looks pretty good from here. As other have mentioned, final evaluation is probably better after the lights are added.