Altogether here, there is about 8-10 hours of additional content, not including every side mission as well as added multiplayer content.

If you liked Red Dead you will enjoy this bonus content

This is an amazing DLC (downloadable content)

In an age where many publishers are releasing/using DLC in controversial ways, Rockstar has proven this generation to be ahead of the pack in releasing substantial, meaningful post-release content, and Undead Nightmare is no different

It's also perfect for RDR multiplayer because it includes a ton of enjoyable bonus content that intensifies the multiplayer gaming experience (including the gang hideouts that were unavailable on the original Red Dead Redemption game disc)