Pros:

Doesn't feel that linear
Custom textures and models
Nicely detailed maps that look great
Maps were designed well
The poster made my day
Gabe flew down here to play it and it was on tv!

Cons:

Trying to thing of one but can't

Conclusion:

With some custom campaigns I play, I just rush them and play them on easy, mostly because they're badly designed and poorly detailed. Except with yours I actually turned up the difficulty and when I died I could actually be bothered to retry because I enjoyed the maps.

I hope your still working on this because the campaign so far is great! You going on my watchlist.