Yeah, I use it. That said, it is not much of a repellant. It does seem to repell those insects that rely on smell to target you, but, not all of them. Like Stephen was saying, it may be that the ones I noticed being "repelled" were already dosed heavy enough to die. It is (or used to be) the active ingrediant in RID or NIX for human use for lice, scabies. The military used it for clothing in the Viet Nam era. I picked it up from a vet ten or more years ago. I believe they still use it in jungle areas.
There are several caveats for usage: The first and formost is that it IS a poison. It will also loosly bond with most clothing. Some cothing does not work that well. Things that do not absorb water do not bond with it. Wool, cotton, nylon, bond pretty well with it. Poly propylene does not bond too well. It is fairly deadly to cats. NY restricts usage of it as do some other states. It is not something you apply in a washer. Anything left over will go through a treatment plant and kill fish, amphibians, etc. Once it is on cloths, and rinsed, it stays pretty good, through many washings, depending on the clothing...it does not wash out. Any leftovers, should be exposed to UV (bright, direct sunlight) for a day or two to break down the remainder. Use caution with any poison, but in particular this one, it kills honey bees, too. A lot of concern centers around it's use in agricultural areas because it kills ALL bugs...good and bad.
Sprays work but more effective is dipping cloths in a 5 gallon bucket. Then, letting them air dry. Then rinsing out the remainder in a 5 gallon bucket. It appears safe enough to pour the remainder on your driveway and exposing it to bright sunlight. Caution should be used around cats, again. It is also sold as a bug dust or ant killer. Normally, concentrations should be about 2-3% for treating cloths. But, since it sort-of acts like a dye, you can effectivly treat cloths with .25% bug dusts. You need to add about 8 times the amount. I have found about 1/4 cup of .25% dust to about 1 quart of water will treat 1 set of clothing: pants and shirt. After drying, I rinse these in a 5 gallon bucket, pouring the excess water on the driveway (after locking the cat in the house for the day.) Then I wash them. I do not do my socks since I wear long, high topped socks. Nor do I do my underwear/long johns. The long johns are polypropylene which does not pick it up that well or smartwool (merino wool) which is worn under something else. In either case, it is not needed since it will be in my sleeping bag, under my pants or other clothing.
I suggest you study up on the stuff and make your own decision. I do not recommend it to anyone without insuring they know the risks. A lot of poisons can cause cancers and other odd diseases. Secondary kills remind me of the older DDT killing off the birds, too. For my time in the woods, I feel it is worth it. You may not feel that way. Use caution and be responsible with any left overs.