Being a regular traveller to Peru I've had the chance to sample the real thing. Mochicas isn't perfect, but overall I love going.
The cancha they sometimes serve before you get your food is great. The papa Ala huancayna is excellent. The llama dishes are certainly deserving of praise.
But what really stands out is the decor.
Definatly worth a visit, if only once out of curiosity. But I'd recommend going twice to sample a few different things