It's a -0. Not terribly far from being at the bottom end of +0, but there's little in the way of the scaling, and there's not really a clear progression path forwards.
9RHD hurts a lot, and any builds that rely on spamming attacks (you do have 7 natural attacks) usually rely heavily on class levels for bonus damage and/or getting pouncing abilities.
The Shattering Shriek ability might be more useful if it weren't single target.
Plus the lack of hands.
Makes for an interesting encounter, though.