I've played a few games with them so far, and they didn't blow the doors of anyone. I just deep striked them down on an objective and shot anything that got close. I also deep struck them down all in one blob so I'm not sure if splitting them up would be a better tactic. I've also only played against t4+ armies with these guys so I'm sure they'd do better vs other t3 armies.
Cons: Pretty squishy, and not much range. Longest range guns are your Lasguns, and Cannon from Nitch's squad. Besides that everyone else has a 12in or shorter pistol.
Pros: With so many characters you have a lot of flexibility on who gets targeted first, etc. The Rouge Trader Vane is pretty sick, she can hold her own in CC, and her pistol can do some work.
Rules not withstanding, they're super fun to paint, and really quick to assemble. They look really sharp and contrast well to any other imperium army you'll end up allying them with.