I've done my own research, and here's what I've found.
There are four health-share organizations that meet the criteria to exempt you from the PPACA penalty. They are:
- Christian Healthcare Ministries
- Liberty HealthShare
- Samaritan Ministries
By law, these are religious organizations and some have have strict requirements for membership. Some go as far as to require that you are a practicing Christian attending worship services regularly with a written referral from a church official!
Liberty HealthShare has, by far, the loosest membership requirements in this regard. They simply require you to sign on to a statement of faith that is so generic that even many hard-core atheists would have trouble objecting to it. Also, being a non-tobacco user is a strict requirement for membership.
Most everything that follows is what I've learnt from my reading about Liberty HealthShare. Altho members pay monthly into a "sharebox" used to pay other members' medical expenses, it is technically not insurance. An insurance company keeps assets on hand that are invested and divested as premium payments come in and claim payments go out. With health sharing, your monthly payment goes directly to pay another member's health costs. (You are also encouraged to pray for the person whose expenses you are paying.)
That monthly "share" amount that you pay will likely be less than you would pay for insurance. They say that they maintain lower overhead costs than insurance companies do, but there is something else to be aware of: the coverages simply aren't what you get with insurance. You may be aware of the fact that these being religious organizations, services that many consider objectionable such as abortion and gender-reassignment are not covered. In their terminology, such services are "non-shareable". Also, any injury or illness that results from drug abuse, sex outside of marriage, or hazardous activities (they mention rock-climbing and car racing specifically) is non-shareable.
It also looks like the coverages aren't very good for chronic illness requiring ongoing medication. Mental health services and durable medical equipment aren't covered. That being said, doctor fees, hospital fees, and prescription drugs are covered.
To use an illness that I'm familiar with, suppose you have sleep apnea.
My understanding is that the fees for your lab tests and consultations would be covered. If you had surgery to correct your illness, it would be covered, but if you purchased medical equipment to treat your illness, such as CPAP, you would pay out-of-pocket.
A big plus is that there is no "insurance network". That means that if you need medical services and want it covered, you need not be concerned with whether or not the provider you see is "in-network". Who you see for care does not affect whether or not your expense qualifies for "sharing".
Another big plus (at least with Liberty HealthShare) is that there are only two age categories: under 30 and over 30. Once in the over 30 category, the amount you pay each month does not increase with age. This could be a great deal for older folks and a not-so-great deal for younger folks. There are also only three group categories: single, married, and family. After you are in the family category, your monthly amount no longer goes up with each child you have.
As you can see, there are many advantages and disadvantages, and I would recommend you carefully read the fine print before joining a health share oraganization.
Edit: In response to @Bacon's comment below, a quick Google search indicates that some of these organisations, including Liberty HealthShare, will negotiate with providers on your behalf, but some do not. As a member of Liberty HealthShare, they provided me with a "discount card", but thus far, no one has accepted it; my PCP simply gives me a cash patient discount which is similar to what I used to get with insurance.