It's not about real life looking, I think the looking is the same, it's about the more or less 50% performance boost it can provide. It will come out this year maybe. Just google its features, dx11 comparisions and you'll see
Upgrade won't be necessary, 290x works pretty well with dx12. Also it is based on mantle, and expect more performance boost for crossfire and sli. I hope these things are true, since I won't be upgrading my gpu for a long time.