If Veidt's peace lasts, he is a hero. If not, he is a villain.
Go back to the very first entry of Under the Hood. In that entry, Moe Vernon wants to make the world a happier place through his novelty items, including a "fake rubber bosom." To his credit he gets a chuckle out of mailman and everyone else to laugh (as he goes insane) for a little while. When he sees how the world continues to a cruel and terrible place in spite of his actions, he commits suicide.
Likewise, Veidt wants to make the world a happier place with his "fake rubber squid." It remains to be seen if his peace would last.
There are several things to suggest that Veidt's new world would be short-lived. His name comes from the from a Percy Bryce Shelley poem. In the poem, an Egyptian king (Ramses II) talks about how his works would last the test of time. However, his monuments are in ruin. In fact, his works continue to be of note because of the talent of the artists he hired and the Egyptian civilization as a whole rather than his own traits and qualities.
You also have the Tales of the Black Freighter parallel to Veidt with killing innocents (both his artists/scientists and the New Yorkers) in order to stop an inescapable destiny. He talks about how he dreams about swimming towards the Black Freighter in his last conversation with Dr. Manhattan. Furthermore, Dr. Manhattan's final words are that "nothing ever ends" (the doomsday clock itself has reset). The very last panel of Veidt has him in doubt and casting a shadow on the wall (which would suggest doubt is cast on his plan's longevity)
All of this would suggest that Veidt's utopia would eventually fail. In fact, Veidt is killing the people who would help make the world a better place, such as Bernie, Bernard, and Dr. Long. With its nod to the Outer Limits episode, the lesson is that you can't scare everyone into becoming allies with each other (at least for a long time). It would take genuine love and understanding between different people such as with Bernie and Bernard's final moments and Dr. Long's decision (after his harrowing but enlightening meetings with Rorschach) to help people out of selflessness rather than fame.