Oddly enough, the screens that are shipping right now do not support FreeSync. In the product description, it's revealed that Iiyama promises to upgrade these screens to support AMD FreeSync and VESA Adaptive Sync at a later date. This update will be provided free of charge but you'll have to cover the shipping charges yourself so calling this a free update is a bit misleading. The exact details of the upgrade scheme will be provided in the near future.
A 4K monitor built with gamers in mind, with a dedicated 1 processor solution to reduce input lag is great for FPS gamers. Also this monitor will support the upcoming AMD/VESA FREESYNC Technology and iiyama will offer a free of charge upgrade service to upgrade your iiyama 4k monitor to support VESA Adaptive Sync for no charge, you will just have to cover shipping charges. Iiyama will release details of this in the near future, but buy in confidence now as iiyama have the first FREESYNC supported monitor and its available now.
The screen is listed at Overclockers.co.uk for just £389.99 (about US$606) but the low pricing reflects the fact that the screen uses a TN panel.