For a console that hasn`t got a system seller so far and its game library is small and not yet showing the strengths of the console, i think 3DS is doing pretty good so far.
After Mario Kart 7 comes out, i think average sales will increase (for next year too) seeing as Mario Kart series has become a force with casual gamers.
Of course, holidays and more games like Mario 3DLand, RE Revelations and MH3G will help 3DS this year and the next.