The actual speed!
The actual speed is disclosed in the datasheet on Numonyx' web site. It is less than 1 megabyte per second (can be as slow as 0.2 megabyte/second). Compare to modern NOR Flash (including the one from Numonyx) that can be written up to 2 megabytes per second.
Numonyx is simply lying to you.
By the way, this "new" product is the same as the "old" one, unveiled with great fanfare in 2008: