This is my first diffuser and I am very happy with it. In fact, I like it so much I bought a second one from this company. This is my personal honest opinion and I get a little frustrated seeing so many reviews on amazon from people who have received free or discounted products in exchange for reviews. I am interested in people like me who have spent their money and bought a product who want to give a review. First, the only issue I have had with this diffuser is that it is difficult to twist on and off when filling. Difficult, not impossible. If you get the hang of it you will figure out how it should go and it will be a little easier. It locks so that the oil doesn't spill, so you can't just twist it on and off like a water bottle cap. Secondly, I have used both high grade pure essential oils and those with lesser grade and the scents and fragrances can fill several rooms, especially the more potent ones. I have never had a problem with being able to smell the oils. Some will call for more drops than others but that is based on the fragrance of the oil. For example, I use more drops of lemon oil than lavender because the lavender has a really strong potent smell. If I put too much in I will have to turn it off more frequently because it's just too strong. Also, the diffuser has two settings. If you press the "on" button once the diffuser will run for about 30 seconds, shut off and then automatically turn back on. It will continue to do this on this setting. I don't want to assume this is what is happening with those who say it "stopped working" but it is possible. If you press that same button twice instead of once, the diffuser will run consistently until it runs out of water. I use both settings depending on how much fragrance I want or how long I want the water to last. The mist from my diffuser works perfectly fine. The other button is strictly for the lights. Sometimes I use them sometimes I don't. You can have the lights off and use just the diffuser. The "on" light stays on consistently. It is just a small red or green button depending on the mist setting so if you need complete darkness to sleep it may be a problem. I am very happy with the purchase. It does the job efficiently and is reasonably priced. The ones from the essential oil companies are twice to three times as much. I have one diffuser for the main area in the house and now a second one for the bedroom. I also think it could be used as a humidifier even without the oil. Glad I bought this.