I use them all the time and think they are great.
Have a look at the "Tiled Enclosure" care sheet at
http://www.herpshop.com.au an you can see how I have used them in conjuction with a flouro.
Greg Fyfe did some research looking at the amounts of usable UV they emit but it is not all that much. Also the practice of removing the glass cover plate in an attempt to increase the UV which is often discussed (including in Greg's original paper) is very dangerous because of the way they can explode when they fail - halogen globes are under pressure unlike normal globes which are a vacuum inside and as such rarely explode.
Thinking about it I have at least one halogen in each of my enclosures.
The other plus with them is that the globes tend to last a very long time.
