They work really well
when they work. I know lots of people have had no problem with them but...
I bought one late spring 2005 and it worked well all summer and kept the bugs down to a minimum, but it wouldn't start after changing a tank in early September, so I just put it away to deal with in the spring. I pulled it out last May and called them and after some troubleshooting they asked me to send it back and they'd replace it with a refurb through warranty. Refurb worked through 2 tanks of gas and then it died the same way, but now I'm told it's out of warranty and I'm going to have to pay.
It's been a lovely boat anchor in my shed since.