I looked rather closely at the Hexblade last night, and in my opinion, they suck. They are very cool, but they suck.
The suckage is in the enormous Stat dependance, and the fact that they don't do either job really well.
Even with their Good BAB, they are unlikely to be able to compete with the other mainstream warrior types. Fighters concentrate on Str or Dex to increase their ability to hit even further, Rangers go Dex, while Paladins chase Cha but can compensate this with Divine Might, and thus still lay considerable smackdown.
The Hexblade on the other hand has suckage spells, that don't increase AC, can only increase Strength with difficulty (all special abilities are tied to Charisma, including the atractive Arcane Resistance), and ideally needs a good Dexterity in order to compensate the loss of heavy armours (because none of his spells increase AC). This funnels the hexblade into being a variant Dex-fighter, but with feats sorely lacking to do anything. The half caster level also means that otherwise impressive spells become next to pointless. The number of spells per day is pitiful.
A hexblade is a cool concept that suffers from lack of spell access, IMO. He can cause minor ability loss in enemies, and that is about it. He is a supporting character, even more so than the Bard.