we should be very very excited!
Hartsock was a huge difference maker for BYU. He is tied with Shawn Bradley for #2 in career blocked shots. He averaged 1.6 blocks his JR and SR seasons despite being a 6'8" below the rim player.
Dastrup is 6'10" and appears to be a slightly bigger body than Hartsock. If he could develop Hartsocks's timing he will make a difference as a rim protector. It's pretty clear that Dastrup will be even better on offense than defense.