The first season of Durarara!!, as a spiritual successor to Baccano!, serves its purpose well. Many of the same elements are here: gang/mafia/yakuza skirmishing, supernatural elements, wide array of characters, even the openings are similar. But As a stand alone series you can see it's own merits in it's effort to give great twists and turns to the series. Very entertaining if you want to sit down and watch a show episodically.
My only complaint is the way the series in a whole handles extreme situations: One second a character is scared for their life, the next everything is fine. Consistancy in plot is thrown out of the window as the series escalates by the end of the season, then when the next season airs, all tension is gone, and we're stuck in a loop more than a spiral.
But maybe this is one of the themes of the show. How even though things are bad, they'll always get better.