This is a challenging loop with some steep climbs and descents. The trail has some lovely views along the northeast side of the loop where it skirts along the river.
Keep your eyes on the ground and pay attention to foot placement. Many prefer a counter-clockwise loop as the descents provide more run-ability.
Running this loop clockwise is steeper at the start but gets you to the high point along the loop within the first ~2 miles. Extended climbs can range in the 10-20% range, but are never longer than 400-600 meters.
The confusing bit to some going this direction will be at an ATV-looking trail that runs northbound along the river leading into the Housatonic River. When coming this direction, simply make a right and head up the path, and you'll start to see more of the blue blazes (this is around 1.5 miles into the loop).
Making your way up, you'll find plenty of views and tons of rocks. It can be easy to turn your ankle if moving fast so caution is advised on the ascent, but more so on the descent. Estimates for the high point is around 660 feet above sea level. From the top, it is a rolling descent with more technical sections and a cool log bridge right before making your way onto a more smooth section of the trail. (Note: On this section there is a weird left hand turn that does not seem to be properly marked as you need to physically turn your head 100 degrees+ to notice the next blaze or else you'll run off on what seems to be another trail).
The trail then dips down sharply to the outermost point on the trail making a right-hand turn at a very visible sign for the Zoar. You then follow along some awesome singletrack high up but right next to the water front. This side of the loop can be the most crowded, but out on the far end, you won't have as many encounters.
As you get closer and closer to the water and progressively lower in altitude, there is a section of large boulders that can make for some tricky footing. There is one last short, but very steep 22%+ climb that is quickly followed by a similarly steep descent. The Zoar Trail
then keeps going, sticking to the left at the remaining trail intersections until you reach the parking lot.