I guess the answer to the title of this article, as with any opinion based question, is “it depends”. Whether anything is worth the buy or not depends on what you might need it for. If you want to purchase one because it is popular then it is probably not a good buy; as would be the case for anything. But air purifiers are good for heath reasons and I would like to outline some of those reasons now.
First, air purifiers pick up pet hair that is left hanging in the air. This same pet hair and pet dander is what gets into your nose and lungs causing allergy and asthma attacks. Although most people do not have a real problem with pets and pet dander, for those who do an air purifier is a really great way to stay and keep healthy. With less pet dander in the air you reduce allergens which also reduces strep throat, sinus and ear infections, and bronchitis. As we all know, these infections can cause hundreds of dollars to treat, take a week or more of antibiotics which also means a month or more of intestinal irregularity and a couple of days off work while you become non-contagious when it comes to strep and bronchitis. So, you can either vacuum and dust at least twice a day every day, or you can get an air purifier to keep healthy.
If you have a humidifier in your home, especially one attached to your furnace, then you should get an air purifier. Humidifiers are Petri dishes for bacteria and mold which love the warm and moist environment. While this isn’t a problem for most people, and vacuuming at least once a week is usually plenty for most people, there are many who need to have a more sanitized environment. You could get a cool air humidifier that ionizes the water instead of heating it, but then you end up with hard water stains all over your walls and carpet, and it doesn’t work as well. Better to stick with the steam humidifier and get a best air purifier on the other side of the house to soak up all the mold and mildew that your humidifier gives off. And don’t be fooled, NO humidifier is 100% mold and mildew free if it uses heat and steam to humidify.
In short, if you are a health conscious person you should at least consider an air purifier. It keeps the air more healthy and removes those nasty allergens, pollutants, and other nasties that can infect your airways and block healthy lung function.