Pros:

 -inventive glyph hunt idea

 -environments are very well done. The limited view makes it harder to find glyphs.

-The boss fight at the end was amazing considering it was done in L4D.

Cons:

 -Although the idea of finding glyphs was interesting, it can get boring after a while.

Conclusion:

 Silent fear did things that I didn't think were even possible in L4D. Definitely download if you haven't yet.