I have a 3DS and 26 games on it. Love the system. It is very good at 3D Augmented Reality games like the upcoming Spirit Camera.
The adventure game I have on it - Hollywood Crimes I really enjoy. There are more adventure games coming - like the 999 Part 2 game (Virtue's last Reward) mentioned.
The Prof Layton clone (Dr. Lautec) has solid reviews - reviewers in general have been good to it. And many really enjoy the game.
I have a Dsi XL that I prefer playing adventure games on. Bigger screens and the screens are of equal size. This system is still getting releases and support.
On my Dsi XL I have 108 games - 86 of which are adventure games and I don't even have all of them I could own. All of these games will play on a 3DS.
We don't see a fraction of the DS adventure games made for the Japanese market. There are hundreds released there we never see here in the US.
For a game system only 1 year old the amount of adventure games on it is fine. We have 2 right now and another 2 to be released within a year. I only have 1 adventure game from the first 24 months of the DS - Trace Memory.
There is a 3DS XL in the works with dual 4.5 inch screens which will be perfect for adventure games. It will also have dual analog sticks.
FYI - Ghost Trick winning best handheld game, best DS game, etc. etc. and "Mask of Miracle" being the best selling game on the 3DS system at launch ensure's a good supply of adventure games on Nintendo systems in the future.
Now Playing - "999" - Dsi XL
"Kid Icarius" - 3DS