I have never personally used one but I hear they work.
I have also heard good things about auto vaccine. Their system uses Chlorine Dioxide to remove smells, bacteria, etc...You can google it to find out more, but this is what they say on their website about ozone generators..
"Other chemicals such as ozone can also physically change odor-causing chemical compounds (get rid of them). However, ozone is also very reactive with many non-targeted materials, such as dust in the air, fabric, and plastic and metals that are in the surrounding environment. Because of these non-targeted side reactions, more ozone may be needed for a particular job in order to maintain a level high enough to react with the odor-causing compounds. Additionally, aggressive side reactions can damage furniture and appliances in the area being deodorized with ozone. Ozone also requires the use of sophisticated machinery and electricity."