HGVC on I drive is AMAZING!!!! We own there.. and much much much prefer it to Sheraton Vistana. The pool at HGVC is absolutely stunning...and the apartments are new and spacious with excellent facilities.
There are not that many apartments at HGVC as they are still building, so you are lucky to get in to be honest.
However, there is only one Huge pool there compared to the 3 or more at Vistana, but there is a shop and activities.. its much quieter than vistana too as obviously its smaller.
If you would like any more info please ask!