Pros:

Good balance bethween recreation of real places and gameplay
A lot of custom content
Funny easter eggs and indirect historytelling

Cons:

Lag on 4th map

Conclusion:

I've followed all the development of the campaign because it was made in an spanish developing website I admin and I've been able to see all the way the maps have changed playtest after playtest.

I live near the real scenarios of the campaign and beside the gameplay and performance issues that forced to change some sites, It's very fun to walk and recognise a lot of places, buildings and other little details you've seen in real life.

The maps are fun, maybe the first one it's a little bit slower than the others, but map by map you note a crescendo in the pacing ending in a final map where you are looking for adrenaline to help you in your run.

It's a pitty that the last map, wich it's the best one in gameplay, have some lag issues, probably attached to the high number of zombies you'll find. But I know they are working to solve it.