Ninja Town is a pretty great game and not many people know about. Funny and a great little tower defence game its worth a shot and you can find it pretty cheap these days. Another great game is Children of Mana which was / is mega difficult to get now here in the UK but its a great JRPG.
I have the 3D off maybe 99% of the time the other 1% is when I use the AR cards. The 3D just doesn't work for me and makes me feel rather ill. (3D movies also do this to me) so for now it will remain off until Resident Evil Revelations. :D
I am not all that impressed by the launch titles I have to be honest. I bought Pilotwings and Ridge Racer at launch (25th March) and put more time into Pilotwings and I do enjoy it but I do find myself not playing them very often.
So far I have 12, 2 of which I know and work with. I have been quite pleased at the fact that almost everyday since I have purchased mine I have managed to find someone with Street pass on. It is a great little feature.
As much as the REmake is quite possibly my favourite game of all time I am quite happy it staying on the Gamecube (and Wii - even though that didnt work the same for me). Revelations, I am hoping will bring the much needed old skool RE to the 3DS.
The purple one is lovely but from day 1 of seeing official images and things of the 3DS last year I always had my heart set on the Aqua Blue as that was the one I seen first. Although if the purple and blue were released at the same time I'd have a hard time picking what colour to go for.