It's hard to believe, given that you rarely see someone actually playing one, but 50 million PSPs have sold worldwide—an install base just barely above that of the Nintendo Wii. Surprising metric, no?
I think the fact that many are questioning the revalance of the PSP, however, is less a reflection on Sony than how quickly things have progressed in the last few years under the pressure of the smartphone market.
In 2005 (when the PSP first reached the US), the PSP was a pretty amazing device, featuring a gorgeous screen, Wi-Fi (a rarity of hand-held tech then) and enough processing power to drive compelling media.
But today, even through reiterations, the PSP is bulkier and less functional than the average smartphone. And while an iPhone game hasn't yet challenged the best of the PSP in terms of depth, I've certainly managed to be entertained for my average 15 minute commute from place to place.
Still, to say this is a PSP-exclusive problem would be shortsighted. Ultimately, I can't imagine using any piece of hand-held tech I own five years from now, but that's not a perspective I had playing Lumines for the first time in 2005, completely in awe of the spectacle. [Kotaku]