Oh yeah, it's horrible! To the point of being useless. The time it takes to get my iridium to acquire a LEO satellite and then I dial in the long number sequence the satellite has moved over and the phone has to acquire another LEO. Let me put it another way, if you are in an emergency situation and your life depends on making that call, just as well throw the phone at the threat, you may knock it out or at least distract it long enough to get away.
I work for the government and they issued out over 35 iridium to folks I work with. A year later almost all of them have been turned back in, mine included, due being basically paperweights.
I wouldn't waste time and money