A very, very powerful upgrade. Probably too powerful. For a mere 2 credits, you can now defend literally any card you want. Some notable combos:
Ash 2X3ZB9CY. You win this trace. They go to trash Ash. Surprise another Trace! Have fun losing 2 cards! Actually, Warroid Tracker combos ridiculously well with any high priority asset or defensive upgrade. Having to endure this is probably super irritating. Probably only slightly less than Caprice Nisei and Ash 2X3ZB9CY. Even after dealing with all this shit, the corp plays Hellion Beta Test and makes the runner even more sad.
Overall I think this is a very powerful card and an interesting replacement for the soon to rotate Defensive upgrades. Hell, maybe even MWL material. time will tell. Oh yeah it can't be Rumor Milled. Fantastic.