I'm not sure if they're a good deal or not. I replaced almost all my lights with compact fluorescents. No, it wasn't for the environment; they actually are much worse for the environment. It was for money and making some rooms brighter. On paper, they save you a bundle over the long haul in electricity and cooling. Also, I put a 23 watt CF (100 watt equivalent) in a 60 watt incandescent socket, and the room is much brighter.
The problem is the lie that they last longer. Talk to anyone who uses them, and you'll get the same story: They burn out a lot. I follow the directions and don't put them in enclosed fixtures, too. Some do last a long time, so it tends to make me think the problem is in the manufacturing. My solution is to try that 7-year warranty. The next time I am saving the receipt, pinning it to the pack, and putting back every bulb that fails. When it's full, I'll send the pack back.
I tried using cfls and went back to incandescent. The cfls all burned out quickly except for a couple I still have in closets which are rarely used. Normally incandescents go for about $4.47 a 6 pack, so 25 cents a four pack was a good deal even if they only last 25% of the life of the expensive brand.
Our house is almost 100% cfl going on two years and we have had ZERO failures. That includes using standard cfl's in the ceiling fans.