Finally having some first experiences with Bitcoin, seems very disappointing.
The fees are very high, and it is very slow. This makes it very impractical for a lot of uses. What am I missing?
You are missing nothing since you are not looking for anything specific.
My suggestion: Spend time on the forum, read the contents in
Bitcoin Technical Support,
Development & Technical Discussion,
Beginners & Help.
You will learn as you go.
Welcome to the community.