Project Ares is usually quite bad. As
tiedyedvortex explains, a blank 4/2 is absolutely terrible given lots of other options, a 5/2 with 1 trash effect is still very bad, and Mandatory Upgrades is better as a 6/2. It starts becoming playable if you expect to take it up to at least 8, though.
Generally that means traps and Mandatory Upgrades in the deck as well. HB has two great advanceable ambushes in faction, and can easily import a third if it wants. The key is that these agendas are worth a mere 2 points when stolen, but when scored for ridiculous values they have a massive impact on the board state. That asymmetry is the reason to play them. You can expand this by also including Project Vitruvius as another over-advance target. Your deck could easily include 9 overadvance agendas and 9 ambushes. Project Ares means that when you take it to 8 counters and pass the turn, they consider the possibility of losing the game from flatline, or losing their rig. And in a deck built on ambushes, the single bad publicity pales in comparison to wiping their rig. The real cost here is having the resources and patience to advance it that many times, and the deck's commitment to a particular style of play.
Compare it to Government Takeover and Vanity Project, where the gain from the steal is basically the same as the gain from the score. You're risking a lot more by putting them out there. Granted, Project Beale would be amazing if overadvanced to 11 (then worth a full 6 points), but its the only agenda available to the faction to overadvance, and it only has Ghost Branch as a native advanceable trap.
So, no, I don't think it's the worst agenda in the game. It's just very niche, with only a very specific deck type that can pull it off.