Consider Full Metal Alchemist. The first anime adaptation was pretty good. Then after it ended, they came out with Brotherhood a few years later, and I think a lot of people were questioning why a remake was necessary, especially since the first few episodes seemed a bit too rushed in comparison to the original adaptation. But by the time you get to the point where the original adaptation diverged from the manga, hardly anyway says they prefer the original anime to Brotherhood.
I'm predicting it will be the same case with this new adaptation of Rurouni Kenshin. The original 90's anime was very good, especially for its time, and I can see why a lot of people are still preferring it to this remake. But unfortunately, after the Kyoto arc, it ran out of manga material to adapt, and the quality of the anime storyline really took a nosedive as it divulged completely into filler content. Plus, the final Enishi arc from the manga is arguably the best part of the whole story, so the fact that we never got to see this represented through the anime, and live out the true conclusion of Rurouni Kenshin is a tragedy. I'm really hoping this new adaptation will be able to produce the entire manga storyline.
For now, with the earlier parts of the story, it's hard to see much of an improvement. The animation is really very beautiful, but not a great deal better than the original which was kind of ahead of its time. Fight scenes are good but not necessarily as detailed or as exciting as the original ones. The focus seems to be more on sword slashes and light streaks than actual footwork and movement. I'm hoping this will improve as the story goes on. Characterizations are much better though, which I think is currently this anime's biggest strength. They made some weird choices with the original anime and while the filler episodes weren't completely terrible, they disrupted the flow of the story and kind of messed up the motivations and actions of the different characters. Karou in particular and Yahiko are much more accurate and likeable in this version I think.
The Jin-e arc was really the stand out moment so far. The final fight scene where we see Kenshin revert to his Battousai persona was chilling. Very good acting and animation there. The differences between Rurouni and Battousai were much more apparent in this adaptation I think. I remember feeling like Battousai in the 90's anime was just an angrier version of the regular Kenshin. This Battousai seems like a completely different character though.
I was also pleased that they did the Raijuta and Yutaro arc closer to manga cannon this time. The changes they made in the original were a bit bizarre and pointless. I'm also glad to see they didn't cut Maekawa and his dojo this time around.
I'm really excited to see where the rest of the story goes. I think a lot will be riding on the fight with Saito, since I know that's a favorite moment from the original anime. As long as they don't screw that part up and give the moment the gravitas it deserves, I think this adaptation will be golden.