Ok, I love Gameboy, I love the Advance, I love the DS, but I have to say, the 3DS tops them all! Everything about it is perfect!!! Everything that comes packaged with it is great. Here are just a few things I noticed about it from the get go.
3D: It's perfect. I'm so glad you don't need glasses for this. Nintendo did it right. And if you get tired of it, you can just turn it down and just play normally.
Camera: It may not be as strong as other cameras but it does the job well. And it is extremely fast. You can even turn those images 3D which is funny and awesome.
Mii's: Just like the Wii, you can create yourself through a Mii (however, you can transport from the Wii to the 3DS which kinda blows)
AR Games: This is superb. The box comes with a few cards and when you activate this mode, things come alive around the spot your DS is pointing at. I had a shoot a dragon that was popping out of my bed!!!
3DS/DS Games: You can still play your DS games which is great (I haven't tested if they can come 3D but I doubt they can cause they weren't programmed for it). I'll have my review of 3DS games in the games section but the game i bought with it is (obviously) one of my favorite all time games.
It's a worthy system. It is a bit pricy (as well as the games) but I love it.