what type of fish are you planning on having? Doesn't look like terribly many hiding/safe places for them, a lot of swim throughs but nothing that would make a scared fish feel safe.
Everyone's tastes will differ, but that last one I see doesn't strike me very creative, looks like a tall wall with some holes in it. Some negative space in the middle would drastically change things up. I'd personally use that overflow as the backside of a cave system of sorts, judging by where the pump is you're not going to be "viewable" from that wall so why not use that space.