Pretty much that. His ult refresh really makes no sense to me. At first we had Garen who deals massive damage when their low (although that damage scales purely with the enemy stats, HP and MR wise so a fed Garen doesn't really have a stronger ult), then Irelia whose Q, while dealing someone OK damage, refreshes on killins blows and now we have Darius, the perfect KSer.
True damage + refresh? Pentakills with this guy ain't gonna be hard. But what do I know? I have'tn played a match with him in it yet so I can't tell if hes OP or UP or balanced.