This little mute mutes a lot. For me it works well as a practice mute. I'm not a professional and don't really know how performance mutes are supposed to sound, and probably there are better ones if you plan on using it for actual performances.
The sound gets very dampened and mellow and maybe takes the fun away somewhat. Like playing a trumpet with a practice mute. It is small and it's design actually permits putting two mutes on the bridge if you want to play in the same room as a sleeping baby.
Bottom line is: This mute does it's job. It is super cheap (like most mutes). So if you are planning to buy one, then buy bunch of different ones and try them out (and keep them). These thingies are small and tend to get lost every now and then anyway.