It's not only the cheap bulbs that take ages to warm up. We've only got cheap ones in our house, but my parents bought some quite expensive 'incandescent bulb' looking ones & they take minutes to get to full brightness.
I reckon that we have changed 4 of ours in the last year & we've not been using them that long. So, I think the claims that they last years and years that were originally banded about are a bit dubious.
My 'issue' with them is that I have heard they use a 'lot' of energy turning them on. I have been unable to find what a 'lot' is. But i wonder if in areas of the house where you might pop in & out and only use the light momentarily, you use more enrgy than you would do with a normal bulb.
Also, they are loaded with dodgy chemicals and can't just be chucked in the bin so I am not convinced they are terribly eco-friendly.
I reckon they will be the minidisc of the bulb world and LEDs will take over in 5-10yrs.