Dramatically stronger than an adept, but otherwise still blech. Adept can only do so much. The hexes have a 30 foot range but the first two are insanely difficult to remove: only by limited wish, wish, miracle, break enchantment, or remove curse. Losing your Dex to AC for that long can be painful. Most of the power comes from combining a divine list with choice tidbits from the sorcerer/wizard list. I guess a warmage with Southern Magician can get some solid mileage out of that? The biggest use I see if for shugenja which draws heavily off of the arcane list, but if you stagger hexer levels you can grab a ninth and add it to your class list (and then pick it upon level up).
Edit: I would be remiss to point that, while most of the hexes are "mind-influencing" and thus immunity is easily acquired, the sicken hex is just necromantic and the save DC's scale insanely if you are Wisdom SAD (10+Hexer level+Wis Mod). Hitting a DC 30+ is easy and at least can frustrate melees who come into range.