The Good
1. Pools are beautiful: Whether it's 98 degrees in June or 32 degrees in January, moving water is great to listen to and enjoy. This is especially true with snow on the ground.
2. Spring Clean Up: Because pool owners often reopen for the season in May, by that point the pool has quite a bit of algae and/or other debris in it. Although this can usually be removed within a couple of days, leaving a pool open year-round means that it won't start to see nearly the same issues, especially in terms of algae, as one that's closed.
The Bad
1. Losing Electricity: Fortunately for us here in arkansas our winters aren't that demanding. However in the event power goes out, a few blankets thrown of the plumbings pipes at the equipment pad generally will suffice. Another option would be to have the use of a portable generator.
2. Cost of Electricity: Although most pool owners now have variable speed pumps, an extra 4-6 months of usage does cost at least a few hundred dollars in most cases.
3. Salt System Will Not Be On: Even though this is not a huge deal, it's one that people often forget, and that's the fact that salt chlorine generators do not work when the water temperature drops below a certain level, usually around 60 degrees. With the cool temperatures though, water sanitation isn't nearly as much of a problem as algae will not grow during the winter months.
If you are planning on winterizing your pool: