We have stayed twice in a rental home and just loved it! In 2005 we stayed at Highland Reserve, it's a little out of the way but the price was right, I think we paid $99 a night.
In 2006 we stayed at Glenbrook Resort I think we paid $109 but added pool heat, the bill was still pretty reasonable for the week less than $1000 US.
Highland Reserve was a 4 bed pool home, Glenbrook Resort was a 3 bed pool home. If you are interested in Glenbrook ensure you get a home with a pool as last year when we were there, the clubhouse and community pool were closed and looked like they had been for some time.
For us it is great to have a week to relax, shop, come back for a swim, site see a little and just laze around. We were able to cook if we wanted to, I cooked breakfast once!! The kids were getting sick of restaurant food and asked for KD one day, it was great to know we could prepare it for them.
Having said that, both years we stayed on site for our days at Disney as it is much easier and we enjoy the parks more knowing that we don't need to drive anywhere's when we're done for the day.