Pros
If you cannot afford a middle/high PHI plan, then the very basic plans are useful for maintaining coverage until you can afford to upgrade. This is particularly important for anyone with pre-existing conditions or those aged 50+, as breaking coverage and trying to get re-insured can mean a waiting period of several years.
Caveats
PHI in public hospitals will entitle you to a semi-private or private room where one is available. Priority is given to those with higher plans, so someone on the very expensive package will get a room ahead of someone on the basic package.
A major problem is that these rooms are often (or usually) taken up by public patients who are critically ill, dying, highly infectious, etc. etc. so you could have the fanciest PHI plan and still be in a ward with 7 other people. There just aren't enough rooms in hospitals, full stop.
Many cheaper plans were brought in by new entrants to the PHI market to attract young people who would enjoy low premiums and would be unlikely to ever claim on the insurance. People often get stung when they go to access private services and find that they are either not covered at all or that there is a large excess.
Cons
Be cautious also with some of the mid-range plans that offer partial cover for cardiac and orthopaedic procedures - the reason for this is that these are the most expensive categories of procedures and the ones that the PHI companies make the lowest margins on. For example, if a cardiac procedure is 85% covered it may sound like a good deal, but it could still cost you thousands.
While cheaper plans look attractive, they can be false economies and the best option, where affordable, may be to get a plan with a higher deductible. In a public hospital public patients pay €75 per night, up to a maximum of €750 per year. If you go through A&E without a GP referral letter then there is an extra €100 on to that.
If you are a private patient in a public hospital then you can be charged even higher fees.
With mid-range PHI in a private hospital, you will face some fees, but often these are not far off the public prices. If speed of access matters to you, then a mid-range PHI is vital.
Of course, you must factor in your personal health history, family history, age, lifestyle, etc.