Have 2 3DS now. Traded in my original DS for a cosmo black 3DS launch day. Just bought the Zelda XL bundle for $142 at Target on turkey day. How can ya pass up a deal like that. I think they are great pieces of hardware, with an outstanding library of software, and I really enjoy playing games in 3d. The new streetpass games really up the ante for a reason to always take it with you on the go, and with MiiVerse coming this month, I'm stoked.
A few friends of mine have a Vita, and it is a really cool piece of tech. I can't justify the expense because, as they admit, they don't even use them often as there just isnt enough compelling software at this time. They always have their 3DS with them.