I like this commercial. So accurate!
Grape-Nuts is nowhere near as healthy as it should be given the texture and taste. Fiber One has got twice the fiber and fewer than half the calories (60 per serving vs 200), and better flavor (for me.)
I used to love Grape Nuts, but at some point they got…softer. 
I know my teeth haven’t gotten harder <quite the opposite>, but now Grape Nuts get soft in the milk much, much faster than they used to. Also, they are not as hard and crunchy as they used to be. Though that is my last recollection, at least 5 years ago. Will have to test them again!
I love Grape Nuts - just had a bowl the other night at 9:00 PM for a hearty snack. However, I just have to use a toothpick afterwards to get at the leftovers - that’s part of the routine. I don’t know if I could manage them without cleaning my teeth afterwards.
Does anyone remember the Mad Magazine panel in the late 1960’s or early 1970’s spoofing the Grape Nuts commercial (“It fills you up, not out!”) There are only 100 calories in a serving, but a serving size is 1/4 of a cup. Their panel showed the fat twin models who ate a cup (!) at a time for 400 calories. I was shocked and had to look at the box to see if they were making those numbers up, but they were accurate.
(Found a site with a link: Grape Nuts Commercial. Here’s the link to the Mad Magazine panel: Mad Grape Nuts)
The very one, cool!