Was also there last weekend, we did Dragon’s back and MBR.
All in all i’d say it’s not too rocky, the first section which is designed to give you an idea of the worst of the trail is probably the most ridiculous because there’s a drop every few yard.
As people have already said, it’s more crazy paving than anything else. We ran middle(ish) pressures and didn’t suffer from any punctures and still had all our fillings at the end.
Not sure what you’re planning to do it on but my missus did dragon’s back on a Specialized Hardrock running standard crappy suntour forks and On-One Smorgasbord tyres and she survived. I ran a Specialized Purgatory Control up front and a Specialized Sauserwind on the rear, as far as I know neither are particularly thick/heavy tyres.
MBR has a few loose ascents (brutus springs to mind and a random fire road half way through. The 3rd or 4th stage on MBR/The Beast has a few rock gardens, if you could call them that, but after you’re through it’s significantly smoother. The last stage, beginning of the end, was also fairly rocky from memory.
Further round Dragon’s Back/MBR you’ve got Lurch and Pugsley’s Bottom which are both ‘armoured’ trails. They make you think a bit when you’re at the top but by the time you get to the end of the stage you’ll wish you took them on a bit quicker. 😀
If you’ve ridden Afan, you’ll think it’s more rocky than White’s Level of Y Wal but a lot of the time it’s completely fine.
A quick you tube search will see you right if you want to guage what the worst of it is likely to be.
Enjoy!