I own them, was part of the Kickstarters, and I have run/played Unisystem several times (more with AFMBE).
First, all the books in this line are very well produced. Great artwork that conveys the modern conspiracy alien supernatural bent of the game.
Second, these books in particular really flesh out the setting. Lots of fluff on top of the new rules for paranormal abilities, conspiracies and alien tech. Where as the main book might be used for a more generic setting, these supplements really nail down the specific setting of the game.
I have been trying to invent a new dice mechanic for Unisystem, as I don't like the d10/implode/explode thing (the odds, the curve...). Outside that (for me) it's a simple well thought out game. The ConX setting is a fantastic backdrop for techno-thriller, X-Files, spy-action, modern supernatural conspiracy gaming.