I think that a party of clerics would have a hard time not because of lack of abilities, but because of alignment and goal conflicts. I just can't see it ending up as anything but a total failure unless the clerics are of the same alignment, have the same goals, and worship the same god(dess). But hey, your mileage may vary.
Other than that, I think they'd do fine as a party. A group of people that can bash the heck out of stuff, heal themselves up, and cast various offensive spells (blade barrier is my fav). And if any of the worships boccob, even better.