I have the huey pro and it has made a difference especially on the laptop that had some pretty strange colors. I look at it more as something that balances the color so it looks natural, more than some absolutely perfect color device.
I like it! Got mine on sale in Atlanta at Inkstop, when I was buying memory cards and I'm not one to pass up a "deal".

I believe the difference between the PRO and the regular is the software and the software features. Check it out?
The system asks for the sensor to be checked every week. It also can read ambient room light, and adjust for that, if you have it connected all the time. With the laptop, I just click "ignore" and haven't used the sensor in months.
It wasn't expensive and served the purpose. I like the way my monitor looks much better now.