We played them a year or so ago. They can be fun but there are some weird quirks that get thrown up.
e.g. Because each figure is a unit, even if a load are bunched together, you can only target one man with an assault weapon.
The already dubious force balance goes right out of the window. It does shake things up a bit, though, and makes you look at the game with a fresh pair of eyes. Some units that are ineffective in a regular game have their uses in Kill Team.
We have started using 2nd edition (with forces limited to 400 points and 20 figs) for our skirmish games. It just seems to work better.