The voices are quite lame.
But I guess the creators of that site were lame too.

I would have liked more cheeryful, sad and, low and angry voices. But you can't do anything about this.

Have they worked up a voice synthesiser, which has 4 different voice patterns? I mean the possibility that the voices are recorded is absurd!!!
They've just recorded some voice patterns an then added some kind of code which makes the sentences sound more natural.
Or....?