It's really not that great. For starters, it's in NU, a far cry from OU. While it only has two weaknesses, one (Ground) is very common, and the other (Grass) isn't too uncommon. It's slow, so while it can Volt Switch a teammate in safely, it runs the risk of getting KOed before it can do so. Its only solid stat is HP, its Special Defense is mediocre, and its Defense is fairly bad, so it can't take physical moves as well. Seeing as one of the most common physical moves is super effective against Lanturn (Earthquake), it'll fall quickly. With things like Landorus, Kartana, Excadrill, and Ferrothorn in OU, it won't last long.
So Lanturn isn't good in OU, there are better choices.
Hope I helped!