Hard to believe it was 10 years ago. I just got back into games (as in playing more than just the major releases) in early 2004 after 18 months or so and remember picking up a magazine that had a blowout of the DS, launch games etc. Decided I needed one so preordered an import US one as the UK release wasn't until March 2005 I think.
Anyway, I remember it arriving and opening the box to make sure everything worked etc and falling in love with it straight away. Original model looks horribly dated now, but the clamshell design was impressive at the time.
That first year of its life was great - Mario 64 DS, Ridge Racer, Warioware, Ouendan, Castlevania, Kirby, Nintendogs (which I imported from Japan on release), Mario Kart, Sonic Rush, Partners in Time, Animal Crossing etc. Plus a few other Japan-only releases too.
On that note, it was a joy for importers being region free, but also having a selection of quirky Japanese exclusive releases that you would expect to find on the PS1 or PS2. Rhythm games especially were in abundance but there was also the other stuff like Jump All Stars and so on.
Overall, I'm not sure if I'd say it ended up with a better library than the PSP, but for me it's without doubt the best Nintendo handheld ever released, the 3DS is doing well but will have to do a hell of a lot more to catch up as far as I'm concerned.