Yeah it is a great place but to be honest you really aren't supposed to be in there without an official Omani guide. There are a few key points to miss so you don't get stopped.
If your serious the best place to start is with Mike Notts guide book
https://www.facebook.com/Advanced-Off-Road-Adventure-Routes-UAE-Oman-1391301034531568/ as it covers a lot of this route. I have done 3 variations of the trip and twice with Mike and for a first I timer down there I would recommend his route and also head to Ramlet Jadilah whilst down that way.
I would love to get into Saudi and explore along and around the old Hejaz Railway a few of my friends did it a few years back and sadly I couldn't join them and now access into to Saudi is alomost impossible.