Pros: stable (heavy but doesn't fall off) and mutes quite well. The sound definitely changes (becomes a bit thinner) but isn't irritating, quite nice for practising since you can still hear the violin clearly. It even feels like my bowing improved a little, maybe because I was using extra effort to make a nice sound (which then requires some extra pressure on the string, too) while practising with the mute, so when I took it off, it felt easier.
Cons: I don't know if it's the bridge of my violin that is a little thick but I wish I could place the mute further on it (which would hopefully result in better muting).
Quite satisfied with the mute.