It's decent.
I bought this after reading the poor reviews, so I knew it was highly likely that I would not be happy.  Going into it with low expectations I was pleasantly surprised!  The "jet" is definitely not powerful enough to provide any kind of back massage; even if you could get it in a comfortable position.  But it's very relaxing having it running, it's not loud AT ALL, a concern I had had.  I don't know if it's the negative ion, or if I'm tired, but I am extremely relaxed after my bath!  This is in no way even close to a real jetted tub, but it's quite nice and a fun addition to a relaxing bath.
Rating: 4 stars