I kept seeing the commercial for these and one day while at Wal-Mart they had them on an end cap display so I though I would give them a try. I normally use the "other" brand that has two alternating scents.
I chose the Morning Meadow Collection, which contained Waterfall Mist, After The Rain and Pure Breeze. They had a few other scents, but this one seemed the most appealing to me at the time.
You have three vials of oil and every 45 minutes the little light will change letting you know that another scent will be used. By it having three different scents you can really tell the difference. The entire room will continually smell fresh, but not over powered. In the past I have been disappointed with air fresheners but this one is impressive.
When the bottles of oil are empty the lights will burn steady letting you know, it depends on the strength you use them how long they last, you can use a low setting for smaller rooms, or high for the larger rooms.