As a replacement for incandescent lighting- sure, BUT Most of the US has a heating season.  What that means is there will be a net zero change in energy consumption in the long run- that heat entering the domicile via incandescent lighting means less heat the heating plant has to produce.  Remove those incandescents for energy efficient bulbs- people will see the savings on their electric bill unless they have electric heat.  Everyone else will likely use as much other energy form used for heat as those light bulbs produced.  For some- not an issue.  But then comes disposal.

If people are truly concerned about environmental impacts, make the switch now to LED lighting- no mercury.)  CFL's would not ever come up again as an option if their EOL impacts were considered first.  This change for LED lighting has only really come about within the last 6 months.  LEDs are the future, and one industrial supplier has broken the light output barrier if you want to call it that.  In one case, a thousand Lumens from a single die, and a Power LED Xlamp capable of 100+ lumens output from one Watt input.

Drop a CFL- what happens?  Granted, mercury is bad- it is the only metal with a vapor pressure, and oxidizes so readily that an oxide layer forms on amounts that can exist as a nodule.  A teaspoon of mercury if not oxidized, could a lecture hall full of people within an hour otherwise.  The amounts used in florescents is so miniscule it vaporizesand oxidizes the moment the envelope breaks.  But that mercury vapor released, while not immediately a problem, does add up in the atmosphere and can precipitate out in rain.  So why contribute to that amount by buying CFL's?  They may be reasonably cheap now- but end of life?  How about light output after a month or two?  In some cases, there is a noticable amount of loss.

Drop an LED array, it may crack in some designs, or it may bounce in others.  Is there any contamination?  Nope.  Then there is the matter of End Of Life?  50,000 to 100,000 hours later- work it out.  That would be a decade from now or longer if left on all day and night, and with even less energy consumed.

Consider in your home- how much storage space do you dedicate to storing your items that reached their EOL?  Then consider a 5 Watt Power LED is about the diameter of a US quarter, and maybe 1/4 inch thick.  This means more room in your closet for EOL items.  Then consider what impact on storage space occurs in an office or institutional environment of 100,000 square feet?  

While the technology still has a ways to go- it is at a useful stage now for true consideration and CFL's lose horribly in this discussion.  Compare 50,000 hours of an LED to the life expectancy of a CFL- the CFL loses at a mere 6000 to 8000 hours.  Then figure time required to replace each one times ten- Now figure Union Scale on that too.  

Dimmability is easier with LEDs too.  CFL's and all florescent tubes can be dimmed via "Pulsed Width Modulation."  In the case of the cited CFL's above- they utilize this technique, and it is resident in the control chip on the circuit board in the base.   A number of manufacturers of that chip use the PWM method for dimming.  (It is also used for stepping up the voltage in cell phones to drive the LED flash module in cell phones.  It is also the fundamental principle for switchmode powersupplies.)

LEDs can be dimmed with PWM, it is less energy consuming than linear regulators or rheostats, therefore more efficient.  Isn't that the real goal?

CFL's are not an answer- just a transitional technology.  Transformer supplies for LED lighting on 120VAC kills the energy savings potential that exists dropping them to the same level as a 2 tube trougher.  The solution I am using in my transition is to supply from a surplus switchmode supply from a computer printer, or other device.