First mission feels a bit less polished but gives a good feeling of trekking through the mountains, it's very original, and completely different from the second one.
Opening the castle gate was frustrating, I went around the castle a few times and was saved by ttlg forums.
Do persevere or skip altogether, the second mission is the main course.

Second mission is outstanding, having visited Neuschwanstein myself, this is just brilliant and the story aligns very well with the real life king/castle.

Attention to details is incredible, the castle feels very credible and the story develops over time, some items/doors/people, move after special cutscenes.

Difficulty is a bit high, there is quite a lot going on, and it can be frustrating going around with all the locked doors when stuck on what to do next.
Luckily Zontik has also provided a walkthrough, which does the job perfectly.

This mission contains a lot of unique things I've never/berely seen in other FMs.

Definitely a mission I would put in the must play list, as it's very memorable and a great example of storytelling.