Pros:

Long maps (I like this)
Interesting Panic Events
Good atmosphere
L4D1 Survivors in L4D2!

Cons:

Riot infected need to be in less of the campaign
Ending finale can get glitchy (but that was in the original version)

Conclusion:

Not as good as the original, but really that has to do with the differences between L4D and L4D2.

Is it just me or is the Bot AI worse in L4D2 than it was in the original?  The l4d2 bots don't handle this map as well as they did in l4d1.

I'm not exactly sure what to review of GeminiSaga's work, but I love that it was ported to still use the L4D1 survivors!