As a guy who finished the original game without co-op mode on, no co-op on this DLC didn't make any difference for me, but for people who are waiting some more time with friends while playing as Ryder, bad news for ya.

As a single player DLC, it makes everything you could expect: some more content to do, not so much content to get and short, very short. It gives another view on the original plot and some surprises (or not), just giving something to expect on the next game... Oh yeah, next game...

In the end, if you liked the original game, this could give you some more reason to play again... if you just want something to play, with the money you can pick something else ans spend much more quality time

This DLC is not terribly long, is single player only and can be BRUTALLY difficult. Zombies seem to spawn endlessly forcing you to find high ground as quickly as possible. Some may like this gameplay change as compared to the original, but it can get tedious. The jump kick and stomp tactic cannot be spammed to victory and melee is almost useless - guns are the way to go with Ryder. Sparse at the start, getting plentiful as the game progresses but you will never feel invulnerable.

Story-wise it takes a few contrivances such as one person perfectly mimicking another's voice in order for the DLC plot to make more sense (names left out intentionally to avoid spoilers) but it manages to add to the main story arc nicely. The areas you explore are all familiar except for a few and the story elements are mostly CG instead of in-game, but it doesn't cheapen the overall experience.

It's a quick plough-through for some extended Dead Island action but a much better value then the Bloodbath DLC.