Stonefly is tough but tons of fun. The climb is steep in places. Steep enough to make me question my 2x10 gearing. The hairpins in some places are so tight that just negotiating them is difficult, requiring full concentration. Otherwise the only other daunting bits are the length and the uphill bridges that have slightly odd approach angles.
The trail is well marked with the fly symbol and 12 on each post.
The climb is challenging and rewarding. The descent is a hoot. Swooping roller coaster curves piling on the g-forces. There are a few jumps that were intended for high speed take-off. I only did the trail twice, so didn’t get the hang of it enough to let it hang out.

If you get a chance, ride Stonefly. It is definitely worth it!