Pros: Bright, better color temperature than incandescent lights
Cons: Heat buildup can drastically shorten life, mercury dispersal if broken while turned on
I've experienced failures of over a dozen of these before I figured out what the problem is. If you put these into the below-ceiling-fan mounted fixtures with glass "tulips", the heat buildup on the electronic ballast at the base of the lamps (since the bulb is base-up inside the cup of glass shielding)causes failure within 6 months. My only solution (ugly and dangerous) came from removing the tulip glass shields and putting just the bare bulb below the fan. This exposes you to mercury poisoning if you break the bulb while it is turned on and looks awful. But after removing the tulips I now have lots of light in my computer room. I don't know what we're going to do when incandescent light bulbs are forbidden. They actually have their place in the fan lights.
These bulbs last well in free air mounts like the typical ceiling fixture, where air can circulate around the base electronics.