Boring
I just didn't find this funny at all. Niven was in movies that were much funnier. Just wasn't what I expected. In fact, beat me up if you like, but I much prefer Steve Martin's version.

Inspector Clouseau's Pale Shadow
This movie is cute and funny, especially in the scenes that feature Peter Sellers. The grave weakness of this movie, the first in this series, is that the emphasis is on the dashing and debonair jewel thief played by David Niven. There's nothing wrong with that, except the character was already a "stock" character and there's really nothing interesting about them either. Niven's acting was great and the leading ladies are lovely. Also, I had forgotten the great musical number in the middle.

But no one can spill milk or break a violin like Sellers. Inspector Clouseau lights the screen whenever he is on.

The Pink Panther (original)
This is the original one that set the stage for the sequels. I was mildly disappointed after seeing this for the first time in many years. It's so different from the sequels. It's a great caper film, more subdued than what the series would later become. There are hi-jinx galore, some of it bordering on slapstick. DVD quality is great & there are bonus features; the main one being a trivia track that informs the viewer of many things that go on or went in the movie, a la what AMC used to do on cable.

Classic British/American comedy which spawned a franchise
One thing not mentioned by other reviewers is that this film, and Peter Sellers' character of Inspector Jacques Clouseau (sounds like someone else, right?), had been meant as a one-off. My understanding is that Sellers was contracted to play a featured part, but not steal the film! Nor was his character slated to develop into a whole film series, resurrecting the physical comedy of the silent masters and emulating the deadpan of the Monseur Hurlot films. Instead, Blake Edwards' hip 60s comedy exploded with Sellers' incarnation of Clouseau, and an even more wacky "Shot In The Dark" (co-written by the Exorcist's William Peter Blatty) was the immediate follow-up. In American TV, we know about "spin-off" series, and that's really what the Clouseau films are: a spin-off of this first classic. The Pink Panther is a must for fans of the swinging 60s comedies like its sequels, like "Casino Royale", "Under The Yum-Yum Tree", "The Graduate", the Flint movies, and others. Favourite scene? The bedroom scene, with David Niven (later of "Casino Royale") and Robert Wagner (of recent "Austin Powers" fame) hiding from the inept investigator. In fact, you can't watch my favourite Blake Edward movie, "Victor/Victoria", without seeing similar classic sight gags and situations from just that bedroom scene! Buy this movie!

The Pink Panther
The great Blake Edwards inaugurated the farcical "Panther" series in 1964 with this zesty comedy caper starring David Niven as a covetous, Cary Grant-like jewel thief. But it was Peter Sellers's brilliant performance as clumsy Inspector Clouseau--the very opposite of Niven's refined, urbane criminal--that made this a madcap classic. Goofy and fun, with an indelible, Oscar-nominated score by Henry Mancini.