I think what's important is having an integrated package of colorimeter and display calibration software that's flexible and gives satisfying results. I didn't want to purchase the Spectraview bundle because it only profiles NEC displays, and I have a number of displays to calibrate: my portable Mac, my wife's portable and office macs, my children's mac, etc.
I checked with tech support at NEC before purchasing, and they confirmed that their bundle only works on their displays. Something like ColorEyes Display, however, supports a number of colorimeters, and virtually any display, so that seemed to me to make a great deal more sense, especially given the fact that the NEC equivalent isn't any less expensive as I recall.