I think it's very ironic that with Wii, Nintendo preached that game visuals didn't matter, and the system sold gangbusters out the gate; with 3DS, the main selling feature of the system (in fact, you could say its raison d'etre) is its game visuals, and the system is struggling early. That's what I mean...I look at the 3DS' feature set, and graphics aside, how is it markedly different from the DS? The eShop is a bit better, but that was there already; it still uses a friend code, so while that's improved it's still a bit cumbersome; StreetPass is neat but nothing overly enticing; the touch screen/stylus setup remains unchanged. If the 3D effects aren't used in a novel way that fundamentally changes gameplay (and that was my impression from my lengthy hands-on time at PAX East), what do you have? A suped-up DS. Maybe Mario Kart will be good enough to make me buy the system; right now what I'm hearing about Super Mario is that it isn't. I'm waiting for an excuse to buy one.
As for Vita, Sony is certainly doing some things that intrigue me. 3G? Hell yeah! They can do some interesting stuff with that, things that really fundamentally affect what can be done with the system. Nobody knows how they're going to handle the subscription stuff, but assuming they handle it in a sensible manner (hopefully entirely free, or free for AT&T cell customers/nominal fee for others, or free for PlayStation Plus subscribers, whatever) it'll be pretty cool. It's at least something different and new to handhelds. I'm also digging what they're doing with Ruin, which is to literally allow you to have the same game span a console and mobile platform. That's really interesting. Of course, the fact that it has two analog sticks is huge for a portable. We can finally get some legit handheld first-person shooters, instead of third-person shooters with assisted aiming and cobbled-together hybrid control schemes. My point is that I can at least look at Vita and say, "It's stuffing a lot of technology under the hood, and doing some pretty new and different stuff...I can see why they're charging $300 for the top-end model". I could never say that about 3DS. All I could do was wonder what the heck cost $250 in that thing.
But then, that's just me. I love gadgets, I love the "always on, anywhere" nature of 3G, and I love first-person shooters, so the Vita's featureset instantly appeals to me. I love my DS to death, but 3DS needs to differentiate itself a bit more.