The stall behavior was carefully tuned to match the real aircraft's performance. The wings on the Islander allow for quite high AOA before stalling, making them tricky to stall. The violent behavior seen in the video above is due in part to rapidly the changing C/G with the skydivers in addition to an already high AOA.
Our testing team, with quite a few Islander pilots on it, feels that the flight dynamics are pretty dead-on, we have a few tweaks coming to improve little bits though, of course.