There is another thread on this subject going today, you might check it out for more info.
Strawbale construction, like is used for houses, IS good for chicken coops. Very very high insulation value, and ddurable. However this is MUCH MUCH more complicated than just stackin' up some bales. You have to have a proper foundation to keep the walls stable and the bales off the ground; then you put the bales together, spearing them with rebar as you go, then wrap the whole thing with chickenwire and plaster over it with cement. Most people don't make the strawbales structural, they just use them to fill in a timber frame.
There is no issue of predators getting in because it becomes essentially a stucco wall.
However this is LOTS AND LOTS OF WORK and not quite as cheap as you might think. (Although cheaper, for houses, than traditional stick building, if you do it yoyrself).
Just stacking strawbales to make a coop is not such a good idea.
Very dangerous (can't tie it together well enough to prevent collapse, unless it is just a tiny doghouse-style hut), will get moldy, totally vulnerable to predators, won't last long, etc.
Strawbale construction (the whole enchilada with the foundation and rebar and cement and all) IS great for building houses, but would only be a good idea for a coop if you like the challenge of doing things differently. THere are lots EASIER ways to build a coop (tho it won't end up nearly as insulated).