I have a TLR-1 on a Ruger Mk II. It works great but I wouldn't personally recommend it for a self defense gun. As another member noted here, it is a bit TOO easy to activate.
I had a small rail mounted to the underside of my (bull) barrel and it tucks up nicely. It's my after dark skunk gun. We have a real problem with them here.
Again, the light and laser work great, but I tucked it away in a foam lined case right after I got it mounted. I went back to get it a week or two later and the battery was dead. I realized, after I changed the battery that it was being activated by the foam lining of my case. I checked it an hour or so later and it was HOT. I'm probably lucky it didn't over heat the first time it drained the battery. Now, I just keep it loose on top of the case in an out of the way place that's easy to get to.
I like the light, and it's perfect for my application but I would have second thoughts about carrying with it. If I ever do, I'll make a Kydex holster for it.