Eh. Depends on how you use them. A psyker battle squad combined with Ratlings will pin anything that isn't Fearless. Ogryns are expensive, but good with Straken and a high-Ld IC on them, since Straken has his counter-attack bubble and they're too slow to guarantee getting the charge. Storm troopers tear up anything power-armored, especially if it's Eldar; the ability to reroll Deep Strike dice and take two special weapons in a five man squad makes them pretty good at the suicide Sternguard role, as well. And Marbo's a deserter; I've never fielded him but I was partnered with a Guard player who did in a doubles campaign once, and he was always too late to make a difference.