They generate a "harsh" "blue" light
This is no longer true, it's a hold-over from years ago, yet it's mentioned in practically every article on CFL's. The problem is that, for some obscure reason, CFL's come in different "color temperatures" which produce different light spectra. You need to remember the magic phrase "warm white" or the magic numbers in the range 2700-3000 oK (Kelvin) which is nerd-speak for the same. And never get Full Spectrum bulbs!
This interesting British study shows that only half the people surveyed could tell a CFL from a non-CFL, and some even preferred the light from the CFL:
We invited 761 shoppers to take the Light Bulb Challenge. The aim of the experiment was to see if they could spot the difference between traditional light bulbs and energy saving ones. Out of 761 shoppers, 53 per cent either got it wrong or could not spot the difference....When asked which lighting they preferred, the majority - 2 in 3 (64%) preferred the energy saving lighting, or didn't have a preference. Only 36% preferred the lighting of the traditional bulb.
They have mercury and are toxic
Yes they do and no, it's not a problem (but see this post about the hysteria it can generate.) Firstly, the levels are dropping, it's down to 5mg per bulb now. That's a lot less than the mercury released by power plants that produce the electricity, so by using less power, you still create less mercury pollution by switching to CFL's. And you don't have to take the EPA warning seriously unless you're borderline paranoid.
They are slow starters and take a while to reach full brightness
Again, a hold-over. Most bulbs now start up with a fraction of a second delay (but IKEA and other really cheap bulbs are notorious for their lag.) The brightness lag is more of an issue, and a neat way to solve it is to have multiple bulbs on the same switch, with one an incandescent, preferably halogen for its efficiency, so you save some power but almost don't notice the initial lower light level. That is, the incandescent turns on and gives the immediate light and while your eyes are adjusting to it, the CFL brightens up.
They don't fit the light fixture.
Mostly not true anymore, CFLs are getting smaller all the time. At worst, change the fixture.