However, it is also making me realize that I really don't like what they're doing with Charlie's characterization. I think it is inconsistent and weak, which is a shame, 'cause, good actor.
I don't find it inconsistent; it's pretty consistent as a portrait of someone who has some good impulses but is fundamentally weak and fairly self-centered. Someone who will often try to do the good thing (help around camp, et al.), but really can't be relied on because you don't know whether the good impulses or the self-centeredness are going to win out at any point.
My irritation is that Claire, a far more interesting character, at least going by her first appearnces, has basically been reduced to a tool to advance Charlie plotlines and characterization. Any moments of what appear to be independent thought on her part invariably turn out just be a platform for Charlie to override them. Claire decides to stay on the beach; it's all about Charlie getting her off the beach, not why Claire would want to stay. Claire gets mad and heads back to the beach; it's a platform for Charlie getting attacked, Charlie being traumatized, for episodes on end. Claire, we get about five minutes of her looking wiped out. Claire decides to let herself be bait to trap Ethan; it turns out to be all about Charlie getting his psuedomacho on by murdering Ethan. We don't get Claire being revolted by him; we don't even get Claire being pissed because she wanted some fucking answers. No, it's all 'Charlie! You're the bestest! What was I thinking, deciding something for myself.'