I have only been able to use it once, this past summer, but lots of people here use it frequently. Overall, it receives very positive reviews here. My own experience was great.
My advice is to read it over well and understand the charges that go along with your bid in order to make a good financial decision. You should be able to get feedback here on pretty much every Orlando area resort listed there. We happened to bid on and win Summer Bay Resort last summer.
Overall, most of us feel that Skyauction offers a great value. For nightly stays, they dont generally appear to be the most competitive choice but for weekly stays (even if you only use it for 5 nights for example) they can offer an outstanding savings, especially if you are traveling at non-peak times.
It's definitely becoming more well known. If you have any specific questions throw them out - you'll certainly get them answered.