Just saw this recently (I'd seen Grindhouse in it's proper form a while back, downloaded it as such as soon as I heard we in the UK were getting fucked over by the Weinsteins).
Anyway, I dug it then, although after the rather fast paced and violent Planet Terror, it's a real gear change, and probably should have gone first in the double-bill line up. Dug it so much in fact, I'd rather like to see it in the cinema-proper when it finally limps over the white cliffs of Dover.
Anyway, saw the extended cut and I really dug it, more than last time. The new footage doesn't add much more Stuntman Mike, but it does add more - and that's the point, both of Mike but also the girls (mainly the girls I guess). Anyway, the dialogue isn't as superb as Tarantino is known for, but I duno, I think that's become a "buzz argument" over the film, but watching it again I appreciated it more and it did feel like classic Tarantino, and what's more, it pulled me in and I actually got into the vibe of the two sets of girls' stories - night out on the town, and in search of a thrill ride.
One annoying thing though, the first half has a lot of the grindhouse scratches and glitches and reel changes and splices and such - but then this almost completely vanishes in the second half, which is really, really, really odd. Is this just an oversight? Is this to suggest it's two movies about the same psycho-tagonist spliced together? Notice that at the beginning the "original" title for the film is shown before it cuts to white text on black renaming it "Death Proof".
Anyway, aside from that one annoyance, I totally dig the film. Out of DP and Planet Terror, it's the one which feels the most like a true grindhouse film. It's fairly simple things that would be do-able on a lower budget (mainly talking, "normal" car stunts and some gore), whereas Planet Terror has a lot of stars (more than Death Proof I'd say) and has loads of gore, lots of big action set pieces and so on - basically, Planet Terror wouldn't be do-able on a grindhouse budget, but Death Proof feels as if it could be (aside from the odd crane or dolly shot which take it beyond the usual grindhouse constraints).
Basically, take a film like "Don't Look in the Basement", it's mainly talking with little action, but it's entirely advertised around the action...so when you look at the grindhouse flicks of the era, and then look at Death Proof, it really does feel like that sort of experience...whereas Rodriguez took certain ideas and then modernised them, while Tarantino tried to emulate low budget exploitation flicks of 30 years ago.
As for the film itself, brilliantly edited by Sally Menke, it really completes Tarantino's vision (I don't think his flicks would be as good without her on board, and similarly his films are probably the best she's worked on...or at least I could imagine her saying that in an interview). The choice of music is typically Tarantino and really works well within the movie, to the point that you feel "this song was made for this scene", not just picked at random. It feels like a cultural experience, many vibes and styles brought together to accompany the on-screen goings-on.
It could do with the odd improvement, and more Stuntman Mike...but considering the sort of films QT emulating, it makes a lot of sense in how it was put together, almost to nerd-riffic proportions, like a checklist of genre themes, styles, do's and don'ts.
All in all, I really dig it.
All said and done though, I ain't buying squat of either DP or PT until they pimp out a proper DVD, with the film as-it-should-be, including the extended stuff allowing you to view 'as-you-want' (a bit like they did with Sin City) and more extras than the separate discs are offering. I'm not ditching cash only for it to be wasted in favour of a better edition a few months later, and I'm sure other Grindhouse fans think the same thing.