Pros:

It gets your adrenaline going which is pretty rare in l4d2.
just all over awesome and difficult even on easy.
close to impossible as it will get.

Cons:

to awesome to have cons

Conclusion:

my team of 3 + 1 bot managed to beat it after 30-40 attempts. takes 11 minutes about for the chopper to come and my teammate held out till 14 minutes and beat it. and this was on easy.