Eh, I don't know about this one. I was a huge fan, and I mean huge fan of the first series with Azula, Zuko and Aang and etc. But this really seems a bit modernized and more on the anime side.
I already said it in this thread, but it's 70 years later. In the original, the Fire Nation was already in an industrial revolution. In here it looks like they are at the equivalent of very our early 1900s. From our industrial revolution to then, it was only a 100 years, give or take depending on where you peg the Fire Nation to be in theirs. That's pretty close to our own advancement, not to mention that they have benders to help accelerate their modernization. Seems pretty realistic in terms of advancement to me, and I hardly would consider the early 1900s "modern".
I remember the Last Airbender was more of a westernized animation that had it's own style.
Are you sure you watched the same Avatar I did? The artwork in this one seems pretty much the same as in the original from what I've seen so far.