This is a good add-on to other workouts. It won't leave an experienced exerciser breathless but it's definitely worthwhile.
Anna, you need to work on your maxims - how about "it's time to rip our abs in this workout so we don't ruin them in the kitchen!"
I'm 64 and have had wrist surgery, so I have to modify anything with planks. I usually do the other modifications too just so that I don't overdo it. Even with the modifications, I can feel a difference now--plus I really appreciate the short time frame (makes excuses harder to come by ;)