I like and use CFL’s where possible. Our apartment complex converted all units to CFL fixtures, free, over a year ago. In the Phoenix house, I’ve switched almost all regular light bulbs to CFL. Fluorescent lighting is three times as efficient as incandescent – so a 20W fluorescent really provides as much light as a 60W bulb. That’s a fact. The energy savings on a whole residence add up.
A few folks object to a perceived flickering in fluorescent fixtures of any type, and always have. Personally, I attribute this to bad ballasts in thousands of older fixtures with the 2-foot and 4-foot tubes. The same goes for hum. With CFL’s, though, occasionally I do detect a slight hum, not objectionable, and this generally goes away as the bulb warms up.