Pros:

It's a long campaign.
The Car Crash on the second map.
The Forest (Map 4) was a nice map.
Lots of different places.
Finale at the train station was nicely made.
Crescendo and Tank Event at the end of the sewer at map 3.
The buildings before the stadium field had a fine atmosphere.

Cons:

Most of the campaign came of as incredebly mediocre and kinda uninspired. The maps untill the forest were pretty bland and uninspired, a really standard city campaign.
Map 2 throws a non-stop horde at you during the event, while it is ****ing dark and a long way to the saferoom in a very cramped hallway.
 Map 3 has a dammed long and very dark sewer, and after that, the campaign throws a Tank headfirst in your face. The stadium looks also really bland and empty, and the van event does not really fit in the stadium. Like the Tank event wasn't enough.
The finale looks great, but it plays not very well, and the area feels too small to mix strategies up.

Conclusion:

This is a review for the campaign as a whole.
The campaign isn't great, but I have to say that it is ported very nicely.

Pros:

Very nice starting point (The Church)
Alive NPC's in the church.
Lots of detail thoughout the whole campaign.
The swimming pool on map 1 was awesome, especially when you have to fight a Tank in here.
Lots of nice easter eggs.
A Jamon to slap zombies with!
Very long maps.
Funny graffiti at some places.
Custom Commons skin.
Spain is different graffiti in one of the toilets, 2 in one room. Indeed.
Creepy atmosphere, especially on a mutated body in the first map.
The campaign poster is really the best I have seen.

The first saferoom you come across, there isnt anyting in there, and there is graffiti saying that some guys took everything form there. Cue their bodies lying 1 feet from the saferoom.

The holy M60 that is floating before the metrostation. It's probably a glitch, but it was kinda funny.

The whole feeling of carnage and despair during the campaign. Barcelona is completely in ruins, the streets are deserted and full of left cars, most of the buildings later on are damaged or are on fire.
And some of the greatest places are barren and aborted, driving really the point home.

That zombie arcade cabinet.
The swan in the sewer and the graffiti beside it are very funny, especially when you see who's in it. (Hint: You probably know him already)
The helicopter that came at the finale with Npc's in it. It felt very climatic.
The second saferoom has 2 graves in it, and a huge text on the walls, but it is in Spanish....
The room before the Finale has lots of Adraline, Chainsaws, and M60's in it, gives a hint on how hard the finale is.

Cons:

NPC's dont say anything at all.
The Jambon isn't a melee weapon, but i heard it opens up a easter egg later on in the campaign....
Spanish graffiti I can't read. Shame too, because it looked like they told something important....
Lackluster Crescendo events.
Non-stop hordes are waaaay to hard, especially map 3 and map 4.
Late Tier 2 weapons (Halfway map 3)
Would have liked a Bull skin for the Tank.

The Bots seem dumber than usual. Especially during events. (Nick, get this Hunter off me, you are standing 1 feet away from me, dont walk the other $"£$ way!)

One car in the metro killed us all when it fell from above.
First it rolled over Nick and Coach, then rolled against Ellis, and then it rolled over me. Made no sense at all.

Finale is very hard, even on Normal, and the Bots seem to have a lack of good nav inside the final building. Coach teleported some how to the chopper when I got there, we escaped, Coach somehow teleported back to get crushed by a Tank. Again, WTF.
Oh, and there was a Tank at the very beginning of the finale.
Apperently, you can die on the rescue chopper, and the bots won't go in sometimes.

Conclusion:

In short: Warcelona is one of the better campaigns out there, but it still has some problems there and there.
I would give it some extra points if those problems were solved, but it is still very, very nicely made.

Pros:

Varied enviorments
Challenging Maps
Foundry Event
Fighting the infected underwater
Seeing the SI ragdoll like crazy off the water
Map 1 is nice
Beautiful Caves
Custom buildings, like the cathedral.
Finale is hard to survive
Nice Panic events
Final safehouse full of guns!
Cruel to place a Witch in the finale.
Full of details
Survivor Dialog

Cons:

Lag at the Foundry
Lag During the Finale
Stupid Bots during Foundry and Lab Staircase
Map 2 is a little too long, especially when you wipe at the gaunlet event. Especially with the saferoom in sight.
L4D Survivors for no apperent reason. And Bill is dead again.
Draw distance seems to be downgraded, some of the buildings in the distance seem less nice than before.

Conclusion:

Overall is this a great campaign, I like going to many enviorments, the maps are challengeing, and they look great.
However, it lags at some points, especially the Foundry and the whole finale, which makes it harder than it should be.
The bots aren't following well in the Foundry and the Lab Staircase.
One of the greater parts of the campaign is the cave part of map 2, which is fun to go through.
There also went great detail into this camaign, like the bodies in crashed cars.