To be honest when the PSP launched in 2005 I never seriously considered getting one. It was expensive, there weren't many great games for it, it was too big to be a "real" portable. And Sony was really arrogant. When people call the PSP a flop they can always go out and quote the things Sony said in 2004 ("getting out of the handheld ghetto" and such).
But over the years the PSP has gotten more and more interesting to me.
One thing Sony does way way better than Nintendo is giving late adopters the feeling of buying something amazing. I bought a PS2 when it was cheap and had a great budget line of games and I did the same with the PSP. There are tons of truly great games you can get for less than 10 bucks. Ratchet and Clank, God of War, Patapon, Wipeout... it's just amazing. Compare this to Nintendo's budget line of games (which basically consists of titles with low development costs the market rejected) to get a better picture.
And despite people complaining about download titles I totally appreciate Sony's move to release their games as downloads and on physical media with the NGP.
Here's hoping the NGP will be just as great a platform as the PSP is right now. We shouldn't let the PSP's current success fool us, though: For the first two years the NGP will be expensive and developers will take some time to realize the full potential of the platform.
I never expected Sony to do such a good job back when that thing launched 
