Though developed for .mil use, it is a solid performing medium-game hunting round for AR-15 style rifles and carbines. It is capable of very good accuracy and performance from carbine length barrels.
Loadings range from 85-120 grain in factory ammuntion from many of the standard ammo companies, with target, hunting, and premium bullets. Considering minimum velocity performance and bullet energy, most loadings are capable to taking deer size game out to ~300 yards. Ammunition costs are, on average, equal to comperable ammo in other cartridges.
Industry support is good and growing, with many firearms or parts makers having something for the 6.8.
Before the crap starts flying too, I will say what the 6.8 SPC is not:
It is not a cheap plinking round, and probably never will be. There is no military or ComBloc surplus available and ~15 a box is considered good for target loads.
Also, it is not a .270 Win packed into an AR-15. The 6.8 SPC shoots lighter .277 bullets slower than its older long-action cousin. That is not to say it cannot still perform very well, you just have to use it within its limits.
Finally, the 6.8 does not fall harmlessly into the dust at 301 yards. The short, fat bullets do not have the greatest BC and do slow down faster than more aerodynamic projectiles, but it can be used to hit targets further than some opponents of the cartridge will give credit. If you need a 1000 yard gun, this ain't it (though I know one user here who has hit at that distance with a 6.8).