I'm on a little over 5 acres & I've got a bluegill/bass pond (roughly 1/2 acre) in my front yard that can't be filled since it's part of street flood control. Generally happy with it, but some random thoughts. Aeration is necessary to keep from stratifying the water, but you still need to worry about muck accumulation and hydrogen sulfide smell coming from bottom waters. I use both a fountain and bubblers, but they require power, maintenance & can be a PITA at times (I have yet to find a good fountain pump that lasts more than 3 years before it needs replacing, but that's partly the fault of original design location of 220 power source (about 300 feet from pond) and chinese quality pumps). Leaves & branches & grass clippings will all wind up in the pond, sink to the bottom and create muck over time. Depending on your topography, be ready for expansion/contraction with heavy rainfall/extended droughts. Think how you will mow the banks or set a border around the pond so you don't wind up with overgrowth in the changing bank zone. Mine get's too muddy to mow with anything I can ride unless there is a long drought, and if I miss the window before another big rain, I can get weed/grass growth too far out to hit with a string trimmer unless I want to fill my waders. Mosquitos will be ubiquitous, but the larvae help feed the fish. If you want decent sized bass, you'll need to thin the fish by catching or they all become stunted. The sunfish/bream/bluegill are basically just a food source for the bass. How cold do you get? Will 6.5 ft be deep enough to let the fish have water instead of solid ice in the winter? I don't need to worry about that in FL, but Minnesota's different. You'll also need to think twice about lawn chemicals as a lot of them will cause fish kills (Hurricane Mattew taught me that one, so now fire ants get borax instead of more effective treatments & grubs get eaten by armadillos until the dogs chase them away for a bit). Depending on the rest of your land use ... you are creating a watering hole for all the wild critters that have ignored your land for now. Depending on what you have around you be prepared for new tracks & things that will eat your vegetation or excite/endanger your pets. Finally, how deep is your water table? If you're not into it or supplying a regular replenishment source you may wind up with a strip mining pit between rains. I have no knowledge of pond liners or what that would entail since I can dig down 3 feet pretty much anywhere on my lot (except the house pad) & hit ground water. Would I put in a pond if I didn't have one? Knowing how much my wife & dogs like the one we have ... yeah. Would yard maintenance be easier without one? Probably.
