The problem is it quickly becomes quite clear the PCs have no chance against this, which may have been helped by the fact our operatives needed huge numbers on their trick attack checks which gave away the very out of tier CR quickly, we could basically never land hits on it, and the one time it managed to attack a PC it took half their life.
It seems like a great making for a terrifying monster to chase the players, but once you see how slow it is the game just becomes constantly backing away from it as you clear the other rooms. My entire table including the GM walked away disappointed.
By the end of the scenario we were just moving to a task, accepting the fact the thing was going to show up before we could finish it because they all took longer than it took for the creature to show up, running in a circle around the facility, and then doing as much of the task as we could again.
And the worst part was because we had to play that way most of us had nothing to do, we couldn't use our characters. It was send the operative to work a computer, or the soldier to lift something since he couldn't go fight the bad guy, and otherwise just stand around.
We tried to get creative with ways to use the environment to trap or slow down the creature for something to do, but nothing worked to even effect it. Our brightest plan was rigging the second coolant tank to blow after drawing it there to buy time to work on a computer only for it to be empty. And the one thing the author put in the scenario that could impact it was the nanite gun that worked off the PC's to hit, and was doomed to miss, so we only bothered with it once.
Honestly, by the end we were so frustrated we just brute forced the last room by throwing controlled undead and robots in the monster's way so it couldn't get to the people working on opening the door and then by spamming summons every round to keep tossing at it.
Pathfinder Society GM. Starfinder Society GM. 392 posts (2,287 including aliases). 3 reviews. No lists. 1 wishlist. 38 Organized Play characters. 5 aliases. 
