I have two of the CREE bulbs. One is a standard 60w equiv bulb, and the other is a 75w dimmable bulb for recessed can lighting.
The cree bulbs have good color, and have a pretty good light diffuser ...... I would say they are a little brighter than the equivalent CFL bulb, and the are instant on. But what remains to be seen is will they last as long as they "claim" to. The Cree bulbs come with a 10 year warranty(If you can manage to keep track of your receipt for 10 years) I've had a lot of CFL bulbs last less than a year.
The dimming is pretty good, but just like we see in our aquarium fixtures, you cannot dim as low as you could with an incandescent.