Saw this once, and I don't know what the allure to it is... maybe I should watch it again.
I've seen it countless times over the years and, although it is very much of it's time and place (like a time capsule of mid '70's New York), I never tire of it. I might not go as high as giving it a 10/10, but it's right up there with Scorsese/De Niro's very best collaborations, so easily earns a 9.
It's an unflinching study of isolation, social ineptness, paranoia and slowly brewing mental instability. Due to the 'slumming it self-parody' he's devolved into since the double whammy of Heat and Casino, it's easy to forget the impact De Niro had on screen acting. He was the guy every other young actor wanted to be at the *** end of the 70's, going into the early 80's. His bravura performance as Travis Bickle (and the stories of how intensely he inhabited the role) was the reason why.
If someone were drawn into watching it solely by such iconic and oft-referenced scenes as the "you talking to me" mirror riff, or the finger flying bloodbath finale, then I can maybe see how they might find the film a slog to get through. It's a character piece, pure and simple. It's not a crime caper or crazy guy on a rampage revenge flick, which is the expectation I think a lot of people who haven't seen it go into this film with now.
For me, the two stand outs have always been the oddly off kilter narration and Benard Herrmans score, which combine to give the whole film a hypnotic, dreamlike quality that's difficult to shake.
Seriously, I would highly recommend watching it again. Preferably, late at night after a few drinks, when you're just lazing around on your own and let the filth wash over you.