Shameless self-plug. What I think is wrong with the warlock as written is: They have too little damage overall. While they can keep going all day, at mid-to-high levels, pretty much any optimized character can beat them with damage. They are unable to take pretty much any combat invocations, given how awesome and useful the other invocations are. They don't get the chance to take pretty much any combat options, unless they sink their feats into it. Which is annoying, as they are supposed to be dedicated blasters. [/2cents]