WHAT?!!!
Are you guys joking, not only do I disagree, but there's an entire course in Uni about him, so of course he left a considerable legacy!
That's not the point. The fact that he was able to make reforms at like a dictator is the point. He also introduced the idea that violence could be used as a political tool (The Gracchi bothers also demonstrated this), and has such a terrible legacy with the Romans that his name would resonate throughout all of Roman history.
For instance, do you think the Senate would've granted Pompey's or Caesar's without Sulla? No! They did so, because they'd fear one of the two (mostly Pompey) would become the next Sulla - they were scared out of their wits that when Pompey, for instance was returning from the east, he would dictate or slaughter them all (there's a good quote somewhere here...).
Sulla's legacy also taught the senate to side with the more 'powerful' side, as this would save them from their gruesome fate - ala, a repeat of Sulla's proscription when they opposed him.
And last, Sulla was one of the first to go above and beyond illegality. I believe it was him he gave Pompey an illegal triumph (you do not get triumphs for Rome. vs Rome battles, and besides Pompey was way too young). Not only that, but he elevated Pompey's status by marrying her daughter (Amelia I think) to him.
There are several more reasons (if you're interested, ask away), but trust me, if there was no Sulla, there would be no Caesar, no Octavian and no emperors.