Are Slavic languages really mutual intelligibility?

I wonder this.Please answer if you speak a Slavic language.I appreciate it.

Partly. Some of them more and some of them less. Sometimes you can see a great similarity in writing - vocabulary, construction of sentence, etc, but it might be difficult to understand while listening somebody's fluent speech because of different pronunciation and intonation. Some of them use Latin, not Cyrillic, but it doesn't affect the resemblance.