I bought this primarily for the Splicers information. The additional classes covered are interesting, but might be a bit difficult to use in actual game play. The Gardener OCC is designed for fortifying a location against the Machine by plucking and planting plant-based Biotech defenses in the ground, but while mention is made of what they need to do to raise the plants to full maturity (skill roll once per day) I didn't see anything indicating how long this actually takes per day. If it takes hours, then they could only tend a couple of plants if they want to to reach full maturity, but if it takes minutes they could tend many, or they could be much further apart. Also, rolling once per day when most of the plants take several weeks to reach full maturity means you will likely fail at least a few times, and each time you fail, you have to roll another (different) skill check, and if you make that one then you get to roll the best two out of three on the first check to recover. Again, no explanation for how long this takes. And if you fail the plant will never reach maturity. I'm not sure how any of the plants every would reach maturity this way. Even if you had a 90% skill (not likely!) if a plants takes 10 rolls you only have a 34% chance to make every one of them, and that's a remarkably low number of rolls to need to make. You could need far more than 30 in some cases. If you have around 50% (possible at first level) you have not realistic chance to raise anything to maturity. And the actual plants themselves have some really annoying rules, like this plants gets 3d6 branches and each branch has 3d4 of this fruit on them, etc. I really like the concept, but the crunchy bits needed to be thought out a little more. I still liked it simply for the ideas it presents, even if I don't think the actual OCC would be much fun to play.
Then there are a couple of additional classes, from a sort of bizzaro Saint that is interesting and flavorful (hurts rather than heals) to the Geneticists that do the actual grunt work around the genepools, from taking care of the young host armors and mounts until they are ready to be used in the field, to modifying biotech to come up with alternate designs and mods. They get pets in the form of failed (as in not quite right, but not truly useless) host armors that they can modify to do their bidding and act as test beds for experiments. They don't get host armors, so I'm not sure I'd want to play one as my primary character, but they could be very interesting in the right setting, or as an alternate for for a Dreadguard.