according to VGChartz (which accuracy has been disputed here, although I don't recall any links, in any case it's the best I tool I know of on short notice)
the original DS sold 2,381,165 units in North America in it's first 9 months.
That means the 3DS is selling at a greater speed than both the DS and the Wii did in their first 9 months. It's no doubt that the Vita is kick ass hardware, I just hope that's enough, I just don't see much of a hype train surrounding it. One thing that Sony does have is Europe, and so you have to take global sales into account.
I genuinely hope the Vita does do better than the PSP. You would hope so as now Sony has a portable installed base, they just have to keep providing compelling content.
as for a 3DS for a straight man
http://www.gameranx.com/img/11-Nov/zelda3ds.jpg