Should the PSP be viewed as a succes or a failure?

[Galaki]

hardware sales: success
compared to DS: failure
meet expectation of Sony: failed

I think the psp has potential. Like PS3, it's early beyond its time, packed with all sort of goodies. Sony expected that everyone would drool all over it and buy one. But the price point weren't appealing to mass market.
IMO, UMD is a failure. Flash memory was advancing so fast, there weren't really a reason not to use it for handheld. UMD not only add weight and size to the psp, it also eats battery for breakfast. It should have been built to be compatible with flash memory and allows firmware upgrade to support bigger flash memory as they become available to the masses.
Homebrew is also a problem. Sony knew/know homebrew is extremely popular for psp, but they kept updating their firmware trying to block out homebrew every version, and continue to do so even they kept failing. Why not just embrace it?
psp is also more appealing as a media device than gaming.
The size and weight, IMO, isn't compact enough to be truly portable.
And the need to buy extra case to protect the psp adds to the size, making it even less portable.

But with all the negatives listed, it still is a very nice machine.