I don't like this thing, and I have a few good reasons for it. None of this new lucario stuff holds any water. I'd have to say one of the saving graces of this pokemon is sand throw because apart from that it has trouble sweeping. Let me enumerate this thing's flaws.
Bad typing: He is weak to fighting, water, fire, ground
he only resists/immune to ghost, dark, and rock 4x, flying, and dragon, bug, steel. Stab physical and special moves can go neutral on him and flay him.
Bad defenses. Hp is tied with mamoswine, but much lower dfenses. Can't hold up in the metagame, thus cannot find a good switch.
Bad movepoool: lack of coverage really hurts, though stabs are often good enough. Bronzong, skarmory, forrestress hurt it bad.
Needs Sandstorm support: with the new weather inducers, this will be more difficult than in gen 4. Withut the sand throw boost, this thing asks to be revenged.
OF course, I'm not saying ti sux, just pointing out glaring weaknesses.
I think this pokemon has most potential is breaking stall with rapid spin, a dark move, and and edge quake, helping out tyranitar. But without priority base 88 speed and bad typing are serious weaknesses.