This is amazing. I, as a DM, have always wanted to run a Sci-Fi campaign and having to homebrew all the mechanics was a daunting enough task to deter me from it. But now this addition has laid out a vast framework of mechanics to work with. A lot of stuff is still kept semi-vague to allow creativity to triumph in sessions. Action-wise almost all the subclasses added are great (Druid, Monk, and Ranger are the only ones to strike me as alright). Roleplay-wise they are all fantastic. The new spells are interesting and I can already guess that one of my players will find a cool use that I've never dreamed of.
Now the stars of this addition are the mechs, referred to as ATUMs (all-terrain-utility-machines). The creators have labored away to extensivly create the systems for maintenance, salvaging, building, and combat. It all makes sense and it creates a worthwhile goal for the players.
If you want a magitech, steampunk, or sci-fi campaign, this is the supplement you need. You don't even need to include the mechs (but you should), this book has so many mechanics for how technology would work and could serve as a template for you to create your own mechanics and rules. I always wanted to run a Sci-Fi campaign, but it would've just been D&D with lightsabers. Now I can create a world where my players can finally use guns, giant robots, and mech magic. If you don't want a campaign like that, thats ok because there is plenty of things to just steal for a boss or magic item.
[5 of 5 Stars!]