The Great Gatsby remake was better than the original. Baz Luhrmann's movies are always visually interesting, and this was no exception. While a bit over-the-top in terms of activity and the music, the era and the world that Gatsby and Daisy lived in was over-the-top. The original is a bit boring and kind of empty.
Leonardo DiCaprio was born to play this role, and was a lot better than Redford. The only minor complaint I had with the two leads in the remake was that both Decaprio and Maguire were at least 5 years too old for their roles, but they still pulled it off. Redford was too old for that role in 1974 too. I wasn't crazy about Carey Mulligan or Mia Farrow as Daisy, so that is a wash. I think both movies should have gone for a better actress rather than focusing on what Daisy looked like.
There was also just something wrong with the original movie's script. It didn't catch the scope of the book, and felt too much like a generic love triangle than a bigger story of class, greed and ambition.