In other words, it has no chance to succeed financially, and the likelihood that we'll ever see something of this nature ever again is slim to none. With that in mind, we should cherish Redline, because it makes good on all the promises made by every glowing review.
What more can I say that hasn't been already said? The animation is gorgeous, the soundtrack is effective, and the story is constantly engaging. As other critics have tried to make clear, Redline isn't the deepest or most powerful animated film ever made. It is simply one of the most entertaining animated films to come out in the last fifteen years.
There's a lot to be said for that, I think. This is a film that you'll want to come back to again and again. In my experience, that's rare. I can count on two hands the number of movies I am willing to watch more than once, and I'd say Redline is the newest member of the list. I think it is beside the point to try to say that this film is "mindless fun" or "all style and no substance". Aside from being arguably inaccurate, Redline is able to combine sights, sounds and motion to create an entertainment experience that could never be replicated with live action. If that isn't the point of animation, then I'm not sure what is.
I'll admit that while the story is effective, it does introduce certain plot elements without establishing them. In that way, it very much reminds me of older anime films which try to cram a bit too much into the length of a feature film. But at no point is any element of the film confusing. You might not get any backstory on what you're seeing, but you know what it is and why it is there. That alone puts Redline in a better class than many of its fore bearers.
Again, I'll echo the pro-Redline critics in saying this - you don't have to find Redline appealing, but you can't argue with the fact that it accomplishes what it sets out to do.And you should wish that someone would take the time to apply this level of craftsmanship to the things you do like. Redline is the kind of film we won't forget come twenty years from now, and for a certain sector of anime fandom - those who found the medium fifteen to twenty years ago - this is pure gold.