Pros:

Very true to the original HL2
Creative implementations of L4D2 mechanics
Surprisingly good bots.

Cons:

Way too hard
Finale takes too long
Very little health

Conclusion:

It was well done. Perfectly immitating the game it was based on. The flaws have nothing to do with the mapping or glitches. Just imbalance. Definately worth the download if you want a challenge or are a fan of Valve in general.