Jes, it's her best core workout! There are no planks (yay!), but you use an 8lb medicine ball (a dumbell can be substituted; for someone new to these types of exercises, you can get a great workout even without a weight), and do a bit of crunches, and a whole bunch of other creative core exercises. It's not the boring old crunch standards that used to be so popular. This is a great core workout. BC's core work is very similar, possibly a tad harder, and does have some plank work. When I want to really work my core, these are the two I go for. PUB and CW core from the IS are also extremely effective.
Sandra