There's a reason PS Vita is falling behind 3DS and even PSP in its first month on the market.
3DS
-Riding on the success of the hugely successful DS
-This contributed to its relatively strong launch
PSP
-Riding on the success of the most successful console ever, the PS2.
-Sony's 1st portable console and real competition for Nintendo portables.
Vita
-Riding on the success of the portable made popular by Monster Hunter. 3DS has a Monster Hunter game in time for holidays, Vita doesn't.
-PSP owners chose a 3DS over Vita this holiday because of Monster Hunter. PSP owners will only upgrade to a Vita once a Monster Hunter game is released for it.
-DS owners are upgrading to the 3DS
-All this adds up to a weak 1st month of sales for Vita. It's not surprising and sales will be low until either a price cut or AAA software releases like Monster Hunter.