DMC3 didnt have much of a story. It wasnt laid out well. All the major events happened in clusters pretty much. Dante goes into tower, fights random demon, fights random demon, sees human girl, fights random demon, gets ass kicked by brother, fights random demon, fights random demon, stalemates with brother and world starts to end, climbs tower for third time, fights lady, fights random demon, goes to hell, fights arkham, fights brother, saves world, boom. DMC4 didnt do much better either. Lots of filler with random boss battles for no reason. The story was entertaining but nothing special --- D-O-G-A-R-S DOGARS!!
I agree that DMC 3's story wasn't really anything special, but it was PERFECT for a crazy action game. Tons of hilarious moments and over the top badassery made for an incredibly entertaining experience even when I wasn't playing! I mean, in what other game does the main character jump off of a skyscraper and randomly get swallowed by a giant flying sea monster? :D