Outstanding, no two ways about it.
'Jackie Brown' makes for a great watch, I personally found the pacing excellent; which is obviously important for a 2hr 30min+ production. The cast knock it out the park, while the story is riveting. It's worthy of the hype, one of Quentin Tarantino's best no doubt.
Pam Grier is fantastic as the titular character, Samuel L. Jackson is quality as well - the scenes that those two share are top notch. Robert Forster plays a much larger part than I was expecting at the beginning, which is only a massive plus as he gives a great performance. You also have the likes of Michael Keaton, Chris Tucker and Robert De Niro involved - I actually would've like to have seen De Niro used more meaningfully.
Not much more needs to be said, I'd only be repeating what everyone else has positively said about this. It's brilliant.