There's only one company. Virtually all cab drivers, paramedics, firemen, policemen and military ranks seem to have one. It's IDF's official phone, I believe.
If all these public safety agencies are using iDEN mobile phones in Israel, I think it's safe to assume that it works well in most areas you will be because professionals like that would not tolerate using a bad system for long. I'm a little surprised to hear that so many public safety agencies in Israel and even the IDF use iDEN there. For example, do the police have separate two-way radios plus their iDEN phones, or do they rely totally on their mobile phones there?
And the Motorola iDEN phones are very sturdy. Not the smallest or most fashionable models out there, but they can take a lot of abuse.