In death? Probably. In life? Heck no. His accomplishments speak for themselves, but they probably wouldn't have happened without Bane. Of course we shouldn't give Bane the credit of creating and fulfilling the Grand Plan, but he does get the credit for creating the oppurtunity (and that solidifies his legacy).
And this is going to be a big surprise, but I believe Sidious is also a failure too, at least in death. Much like Kun and others, he became too self-centered and attached to his power, so in the end when he was betrayed he left no legacy for the Sith - with his death the Sith Order was completely destroyed. I also believe Sidious never created a holocron, so all that he uncovered in the ways of the dark side were lost (correct me if I'm wrong.)
In my opinion, the Sith Lord who accomplished the most achieved the greatest success was Darth Bane. In life he achieved his goals of wiping out the old, weak order, and establishing a new and far more powerful one. He accumulated a extensive power base and well as uncovering many secrets of the dark side that laid the foundations for the future of his order. He trained a powerful apprentice, created a holocron and solidified a legacy for himself and for the Sith that would be felt for millennia to come.
Darth Sidious left his mark on the galaxy, not only in his Galactic Empire, but also his teachings. Particularly in his trilogy of books titled 'The Dark Side Compendium'. In these books he discusses controlling anger to unleash the full power of the Dark Side, using the weak to gain power, as well as using Sith arts to create terrifying monsters. He also made other writings where he discusses choosing apprentices.
Not to mention being the gatekeeper of the Telos Holocron. So he did leave teachings behind.
Edit: And before you ask, the threads on Sidious' teachings are in the works.