Yes I suppose so, the swathe of chaos and violence he carried through the universe had damaging effects on the Jedi Order and the Republic. But in the end that only puts him on par, in terms of accomplishment, with the likes of Sion, Nihilus, Desolous, Kaan and yes, Darth Malak. They all reaped destruction on the galaxy that the galaxy eventually recovered from, but in the end they were nothing.
In my books, he is a failure.
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.
Didnt Sidious create the book of sith? And I agree sort of with Bane in terms of accomplishments, he is the true Sithari and greatest of all Revanites.