He's not really that great in OU, and can be easily taken out by the common Water, Ice, Ghost, and semi common Grass and Dark types. If you plan using his No Guard ability to abuse it in OU, Machamp (from former experience) will do a better job than Golurk. If you're looking for a Stealth Rock setter, SDef Jirachi or Heatran can do a better job at it.
However, if you are desperately looking for a surefire way to take out Terrakion (Scizor could do it, but oh well), then Golurk completely walls the hell out of Terrakion.
So in conclusion, Golurk isn't that great in OU.