Not that there was anything wrong with the original except for Glen Campbell. Wayne seemed to think he needed a young singing star in his films to get the teen audience in the theaters. This led to such things as having Frankie Avalon in The Alamo. Yikes. That being said, I think Ricky Nelson did just fine in Rio Bravo, and Fabian was very good in North to Alaska.
But I digress. I liked the original movie version just fine, and I like Coen brothers version an awful lot. In some ways it's the same movie. Some the shots are the same. The shootout in the meadow is almost identical. The dialog is pretty much the same too, and it follows the same conventions that the book and first movie do (no contractions). But the tone is different this time. The big difference to me is that Wayne played Rooster Cogburn for comedy. Jeff Bridges plays him more or less straight, and he's a scary guy. The new movie is still very funny, but the humor's not nearly as broad as it was in the first film.
The current movie also uses the book's framing device, with Mattie doing a voiceover at the beginning to let us know that she's now an older woman looking back at an incident from her past. The ending uses the voiceover as well, and I found it much more evocative that the ending of the John Wayne version (though that ending was appropriate for that film).
The actors are uniformly fine. If Hailee Steinfeld isn't nominated for a best actress Oscar, there's no justice. And I wouldn't be surprised to see Bridges get a nomination, too. The photography is stunning.
If you think the western's a worn-out genre, if you think it can't still generate power and show beauty in tough situations, see True Grit. I think it'll prove you wrong.