This trail is labeled as "Black DIamond," and it's strictly based on some very steep and punchy climbing/desending on the southern half of the trail. There's nothing else that is above beginner/intermediate, and the steep climbs can always be "hike-a-biked." It could also be argued that descending the last 1/3rd going North to South does require some braking and bike control skills, and there is a pretty substantially steep hill that wouldn't be fun to roll down if you crashed and "exited stage left."
A tale of "up and down." Either direction, you're going to climb up to Sandurst Dr., and then descend the opposite side.
South to North: You'll climb up some very steep sections on your way up to a paved road, Sandhurst, that bisects the trail into a "north section" and a "south section." Once you reach the paved road, a very nice flowing descent will follow with a rock kicker jump, and some nice rollers and a few doubles. There's nothing that can't be rolled. Once you reach the creek crossing at the bottom, following a hard right hand turn to watch out for, you'll have a combination of ups and downs with some nice berms to help maintain speed. Many would argue that this is one of the most fun descents in the entire Back 40 system. The end of the trail "T's" into Pinyon Trail.
North to South: This direction starts with a much less steep, gradual climb. Once you get to the top, you'll cross a paved road. BUCKLE UP. From here, it is a VERY steep, loose descent that is over in the blink of an eye. There are a few places to catch air, but the trail is a very steep grade and you would want to be a pretty accomplished rider to attempt some of the doubles here, because of the speed required. The trail "T's" into Rago
Most of the locals I speak with prefer the South to North direction, as labeled on the map outline, because following the very difficult climb (that will result in most riders walking at least part of it), you are rewarded with a fun, flowing descent that takes better advantage of the elevation change. It's actually closer to 1/3rd climbing, and 2/3rd's descending if you are going South to North.
However, I'm sure there are some riders who prefer the longer climb, and blazingly fast short descent going North to South. Either way, it's up one side, and down the other with a smile on your face!