my father has one we built 20 yrs ago when we put addition on shop.we piled up the dirt and dug a pond, his has about a 12' water fall running down into the pond. way more work to take care of it than its worth in my mind. i'm with bennie on this one, my water feature is a 18x32 inground with a whirlpool and fountain. not to much work to take care of and i can jump in when i get home on a hot sucky day. spent 4 hours in it on the 4th with my 8 yr old. could not do that with a pond.
I looked on the web and can rent a Dingo, a walk behind digger, for a pretty decent rate, like $170/day.
Could easily dig a pond out in 1 day, and save my old back wear and tear.
Whadda ya think, ever use one, they look cool.