Alright i played through it and i think there are a few major (and some minor) points that need to be addressed.

Major point 1: there is a warehouse toward the end that is using all the same brush work as the one in DT2. i personally think it is bad practice to copy valves brushwork with little to no alteration. because this is still a beta i will not criticize this point any further.

Major point 2: the beginning of the campaign starts off in an enclosed valley, i had trouble finding the pathway out, it needs to be marked better in some way. perhaps by lining the end of the subway car to point right at it, and or by removing some of the tree cover.

Major point 3: none of valves campaigns have 2 panic events and a car alarm in one level (none have a panic event in the first level). this seems like it will be frustrating to players i would advice removing one or both.

Minor point 1: some of the barricades you have used to block the roads and stairways seem a bit out of context. i personally have trouble coming up with good excuses for barricades and therefor will not blame you.

Minor point 2: the game seemed to run a bit slower then normal on my system, i did not inspect the visleafs but i suspect pore optimization is the resign. this can be fixed with properly placed hint brushes.

Minor point 3: some of the details in the map could use a bit more work such as the wood fences between buildings. try using one of the wood fence textures instead of the pointy tops.

that's enough for now good work. i hope to see more of our work in the future.