First mountain trail - lesson in humility

So... I ran my first organized mountain trail. As short one, UTMB Eiger Trail E16 (~17K & 950 M+ elevation). It was a lesson in humility.

I'm an experienced road runner. I've ran 7 marathons and I don't even count the halves anymore. I've done some ~30K trails in my home country, the Netherlands, which is flat as a pancake and Belgium. During holidays in the Alps I've done some mountain trails, also in winter, with snow spikes.

My planned preparation was already minimal, but completely fell through as I twisted my ankle five weeks in advance. And the night before the trail I had to visit the toilet more times than any person would have liked. But I was still there at the starting line thinking I would just bank an easy 17+ K.

I was mistaken. It took me over 3 hours with lots, and I mean lots, of walking and hiking.

The atmosphere was great, the race was very well organized, people were nice, the scenery beautiful, but I couldn't really enjoy it. I'll be back it someday to replace this experience with more happy one, because it feels like it could be so cool.

Regardless of preparation I expected the course to be more runable. Is this also a case of ill-preparation or is Eiger known to be extra steep?