Brian Gibbons
Explorer
Well, if the DM plays tothe fighter's power, then, yes,they are impressive. But they only getone immeidate interrupt per turn, not for each monster's turn. So the first monster shifts, and might get stopped, but after that every other adjacent monster can shift and then move away.
That's a common misconception, that a fighter can stop a shift. A fighter gets to stop movement with an opportunity attack, not his combat challenge attack. If a marked target shifts, the fighter may (if he has an immediate action left) get to make an attack, but the creature still gets to make the shift.