Speaking to GamesIndustry.biz, Tretton said, “In this industry, you can’t get too high or too low, because it moves very quickly. I think there’s an acceptable number – and [the number] we’ve sold: That’s acceptable. If it was triple that, I’d be happier. If it was one-third, I’d be disappointed.”

While that’s not the most enthusiastic response to the handheld’s performance thus far, Tretton does remain optimistic for the future of the handheld. He notes that the PlayStation 3 had a similarly less-than-stellar launch, only to grow into the “incredibly popular and profitable device” it is today.

“Anything with great rewards is going to come with great challenges. We felt if the tech was there, and the game support was there, then the audience would be there. … I feel much better about it now than I did four months ago.”

Tretton’s statements come a week removed from SCE UK boss Fergal Gera’s saying that the Vita hasn’t “hit the spot with the killer software just yet.”

Earlier today, we learned that Sony is “having a more difficult time than [they] had anticipated in terms of getting support from third-party publishers” with regard to the handheld, according to Sony Worldwide Studios head honcho Shuhei Yoshida.