I did not do this myself, it was done by professionals, cost too much, and I love it to death. Took 2 weeks from scratch, only thing there before was the two retaining walls. Comments of all types are welcomed, I really want to learn.
The pond is about 2.5 feet in the deepest area, and about 1.5 feet in the shalow areas. It is more for the waterfalls, i have no plans for koi or anything like that. Right now It's got a few mosquito fish to take care of the bugs in the summer. Later, I am thinking some shiners maybe.
It's got a skimmer with a pump in it, hidden under a flat removable rock, so it's invisible. And on top of the waterfall is a pressure filter, with a removable flushable carthridge. Pretty simple. Nothing crazy. The project started as a waterfall project and the pond got a bit bigger with it.
Plant some bamboo around it. Find a short variety for on top of the wall and a taller variety for the pond level. In a couple years, that ugly wall will be invisible. I have 3 varieties around mine now and it makes a huge difference. Just be careful if you plant the runner type. They might run into places you don't want bamboo and pop up there.