Pros:

o    Beautiful, detailed environments
o    Nice environmental variety, keeps campaign interesting throughout
o    Excellent use of environment to create fresh challenges on every chapter
o   Challenging but not overbearing

Cons:

o    Most chapters are too brightly lit, not enough moody lighting to create a sense that this is a zombie apocalypse
o    A few bugs here and there, nothing game-breaking
o    Maps, especially the bridge area, have a few areas where getting stuck is a problem
o   The gnome disappeared through the floor a few times trying to carry it across the bridge
o    What's the secret to the gnome?!?!

Conclusion:

It's a sad fact that many custom maps and campaigns are mediocre or worse, that's why it's important to leave positive feedback for those campaigns that not only surpass the mediocre but demonstrate a level of professional aptitude that it could be its own DLC. 

Day Break is one of those maps. 

Day Break is a Valve-quality map right up there with Dark Carnival or Cold Stream. The attention to environmental detail, and the variety of environments makes this a fun map to play through. The map-maker took advantage of many different tricks and techniques to create a challenging but fun campaign that rarely gets stale. Save for some "quality control" issues in a few places, this is a great map that really should be brought into the Left 4 Dead 2 fold, much like Cold Stream.

Other than that, the mapmaker could have been a little more aggressive with moody lighting. With the exception of the finale, maps are brightly lit, which is fine but could have been improved with something more ambient befitting a zombie apocalypse (not necessarily dark, but something more akin to The Parish).

Regardless of these quibbles, this is a fantastic campaign that everyone should play.