i got my Nintendo 3DS couple of weeks ago, and i love it. i've been a playstation only fan for a while, but there are just so many cool games which are exclusive to the 3DS system. there are some great games for it like "Resident Evil Revelations", "Dead or Alive Dimensions", and i've especially liked playing "Super Mario 3D Land". definitely worth having.
I agree with Steve. I bought mine shortly after the launch, and now play it more than my consoles. Great retail games to look into are Zelda:Ocarina of Time 3D, Mario 3D Land, Mario Kart 7, Kid Icarus Uprising. Great downloadable titles to look into are Freakyforms, Pushmo, Mario vs DK: Minis March Again, and Art Style series. There are currently 10 game demos to download free (including RE:R), with at least 4 more coming later in the year. Also, the following apps are free to download: SwapNote, Nintendo Video, Netflix (needs streaming membership), and Pokedex 3D.
P.S. NSMB 2 comes out the middle of August, Amazon has it listed, but their release date is currently wrong.