With its citadel and its castle, Kerak is an ideal place to stop off, half way along the road between Amman and Petra.
There isn't much accommodation on offer in Kerak, and it's not worth spending the night there. Simply stopping and exploring is sufficient, arriving on the journey from Amman and continuing toward Petra.
Depending on how much time you have for your trip to Jordan
, Kerak can be an interesting place to visit between Amman and Petra.
If your schedule is a little tight, however, it's better to continue your journey without stopping.