I'm quite baffled by all the bad reviews; the default voice is indeed uncomprehensible, but changing it to one of the (many!) Piper voices actually gives you an output that's easy to listen to and quite enjoyable. English voices' output is, in my opinion, almost on par to Edge's TTS.

While I can't speak for all the other languages, I can say that at the moment the Italian Piper models are a bit lacking compared to the English ones, but they're still comprehensible.