I'm a ELO booster, I boost out friends at bronze with only solo Q Darius. I've been playing Darius since 2 months before the juggernauts rework.

Now, about Darius's play-syle: Darius, or as the "Bronzies" call him, Lord Dunkerus Cancerus: HE is a massive lane bully, early lane pressure and his outstanding substain due to Q allows him to just complete **** on other top lane champions. And if you don't like this play style of a big lane bully, Darius isn't for you

Pros

-Massive Lane Bully
-Early powerspikes
-Naturally Tanky
-Obnoxious Damage
-Burst
-CC
-Easy to pick up
-Very snowbally, easy to comeback from lost lane

Cons

-Low mobility
-Hard to master
-No real hard CC
-May get ganked early
-No hard disengage and engage
-Little Range

Generic Combos on Darius

E->AA->AA->W->Hydra->Q->R
E->AA->W->Q->AA
W->AA->AA->E->AA->Q->R

This is a very easy thing to pull off that gives a hard early lead to you.
It basically revolves around a W start, running to lane(Try to get mid to leash jungle if needed),
getting to the farthest bush,waiting for minions to spawn, and then walking up to your lane opponent, autoing three times, proc Battle Trance, W-Proc Stormraiders, AA-Proc Noxian Might, AA again to ensure extra damage, Flash->AA-only needed to finish off tanks

TL;DR: Pick Darius, bully early, win lane, destroy 2 towers, team fight, fall-off, farm, fight, fight, Win