From the outset, the PSP had the advantage. Sony hyped up it's little machine as the "adult" portable, and successfully skewed the public view of the DS as "kiddy" even before either of them launched. It was a great tactic, but Sony failed to capitalize on the major drought Nintendo had with new games, and allowed Nintendo to release Nintendogs, with nothing to rival it. That game, I believe, turned the tide; it showed female non-gamers, and adults that the DS was capable of some immersing experiences.
So yes, I believe that exact moment gave the DS it's "charm". Even though it was underpowered and supposedly "kiddy", it proved to be great fun, and that right there is the charm- it's actually fun. Don't get me wrong, I own both a DSlite and a PSP-2000, and I play both equally, however, I find the DS to offer more fun with software that does a great job of taking advantage of its features. The PSP is more of a "Hey! I have a widescreen, and I make pretty graphics!" machine to me. Yeah there are some great titles on the PSP, however, those titles have a 9/10 chance of being an existing franchise scaled down to portable level; it's a trait I am not particularly fond of.
Adding a touch screen functionality would really help Sony at least stand a chance against the behemoth "kiddy" DS, however, as we all know, Nintendo can't get enough of innovation. What that means is, while Sony plays "catch-up", Nintendo will play "innovator".
To be completely honest though, the features don't mean a thing if the software isn't there to utilize and reinforce the concept behind them. Gimmick or not, DS has proven its features to be the future for portable gaming.
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