A newer version of Waterfox (64-Bit) is available.Or, Learn More About Waterfox (64-Bit)
Full user review
"Not impressed enough to stick with it."
None readily apparent - no noticable difference in speed or usability - seems to me to be less smooth than FF
Some FF extensions don't work with Waterfox and when you revert to Firefox to use them you have to install them again.
Why would you accept less functionality of extensions etc. for no discernable benefit.