Overall, pretty good. It's got a lot of unique ideas and generally is fun to play. I'll go in detail per map.

Map 1: The poster names are inaccurate first of all. In regular campaigns the names at the bottom follow a left to right order of the survivors present in the poster, which this doesn't so 0/10 ♥♥♥♥ map. The survivors just chillin' in the intro is pretty funny, but the overall sequence looks cool. I like the effort put into survivor dialogue in the campaign in general. If you ever want a more in depth talker set up for it, I'd be happy to do it. I feel like you could've used the escape music at the start as well but idk. The colour correction used is a little too vivid in my opinion and can definitely make things a little too hard to see. The mixing of the L4D1 and L4D2 common infected is a little odd and kinda annoying cause every time a L4D1 common loads my game stutters. For the first door you enter I feel like some marking that you're meant to go into it or it being open would be nice as it kinda blends in otherwise. The barricaded room could have a feature where its openable once the survivors get to the other side of it to open more path ways in the event of a tank spawn that I had here. I think the place where you get the tier 1 guns should also have the 4 medkits included instead of them randomly appearing as the map progresses. The humvee car alarms should have the car alarm glass on them to tell the player that they're alarmed beyond the survivors mentioning it. The hole to get into the sewers should be a little thicker as you have to employ surgical precision just to get on that ladder. Other than all that though the map is nice, I like the travelling from the roof to ground thing set up.

Map 2: The wildly different colour correction is very jarring right after the first map's. Generally making the colour correction less strong would help. I feel like this map could've been split into 2 as it's very long and having the double tank fight right at the end would make dying there miserable. The opening tunnel section is a little boring. There isn't much to distinguish the different areas so it's essentially going through corridor after corridor Doom style until the subway. Having something beyond just the water death room would make it more memorable. I like the barricaded room with the hanging corpse, it's cool. I think having to take an immediate U-turn upon entering the subway is a little silly and going straight ahead would have made more sense as the survivors face that way and the carriages are open and lit up. Having to blow up the gate is cool. I think the items you collect appearing at the gate as you collect them instead of all at once at the end would make it easier to know how much you're actually meant to find though. The railing to leave the subway is a teensy bit too tall making it hard to jump over as you have to jump around the using the lower stairs. The double tank fight at the end is neat although cruel to put right at the end. The bots do like to suicide by running directly at the tanks cause they want to get to the saferoom though lol.

Map 3: Again, relax with the colour correction. The finale itself is good though. Having to wait for each of the cars to fail lowering before being able to press the next button is a little annoying as you're hammered with commons in a spot you only have one way to get to and it's far. Everything else is alright, although very easily camped in certain areas as the commons can only come from far away. The double tank at the end is a little unnecessary btw.

But it was a nice campaign beside that. I've been made to play considerably worse before. I made a video of me playing through it that showcases some bugs I found like dev textures and god spots.
Here: https://www.youtube.com/watch?v=rI2SkIYgTb8