Gritty, beautiful, and one hell of a good time.
Graphically, the world of RDR is designed with more detail than has been seen to date - the attention paid to color, lighting, texture, and mood are simply jaw dropping. Getting the ambiance of this gritty and beautiful place so perfectly sets this game apart from most.
On top of the striking artistic value, the game itself is damn fun. The core missions are varied and entertaining while serving to move the main plot along. At the same time, the many side missions help to fully enrich the RDR world as a whole.
Besides being prettier than previous GTA style games, gone are the difficulty spikes that plagued previous games. I also felt that the save points were managed better than previous games.
GTA IV raised the bar for open-world, sandbox style games with interesting characters and story. Red Dead Redemption has pushed that bar even further. This game is a MUST own.