The premise that our collective fears could manifest as physical monsters is SUCH a good hook. The creatures and their ecology are frightening. The art and the writing are effective at making your skin crawl. I can't speak to how this Data Packet's crunch plays with SLA's rules system, but the stat blocks are straightforward enough that I could easily translate these creatures to other systems.
This is an awesome supplement that you could easily cannibalize for any horror game (fantasy, modern, anything!). I highly recommend it!
[5 of 5 Stars!]