Pros:

pretty long maps, well detailed, good variation. plenty of ammo and health kits, good amount of hordes at the right times

Cons:

mazes and back & forth action is a bit predictable

Conclusion:

not overly challenging, but i played on normal and it felt pretty right.  Lots of fun, I really enjoyed the long maps and I liked the variation in the maps.  Most of the time it's light out which is a nice change from all the really dark maps.  All in all, a very fun map.  Pretty good ending too.