I have just been introduced to Dexter, and I love it!
Julie Benz does a great job. It's weird for me to see her playing such a mousy character (you're right; mousy is the word for it). She's nothing like Darla, but of course she has the same face, so half the time I find myself wondering why she doesn't just reach out and eat the b*tchy neighbor with the yappy dog or the drug dealer guy who stole her car.
That doesn't mean I'm not totally buying Rita, though. I just watched the Halloween episode, and J.B.'s acting really touched me. There's a line in which Dexter says "What are you doing?" and Rita replies, "Whatever I want" that really gets to me. I was gonna say "blows me away," but... nah. Anywho -- she's so earnest. She's really trying very hard to get past the abuse and to be a good mom and a fully functional human again. I believe it. I totally believe it. And it breaks my heart, because the poor girl has terrible taste in men. She thinks she's doing the healthy thing and moving on with Dexter... but he's a serial killer and a sociopath who's doing some freaky mom transference thing with her! It's just so sad. Here she is, trying to take a stand and reclaim some semblance of normalcy and sexuality, and I'm watching the whole time going, "Oh honey... you poor thing. You are just so WRONG."
Kudos to J.B., man. She's really tugging at my heart strings.
The show as a whole is incredible. I love, love, love Dexter. I have a thing for sociopathic characters, so the title character has me rooting for him even though I'm completely disgusted by him. I hate that he kills people. I don't want him to do it. I think it's gross. But I love everything else about him. I love the way he thinks. I love that he fakes human emotion and interaction and that he is totally mystified by just about any and every emotional thing. I love the serial killer stalking another serial killer thing. Basically, I love it all. The minor characters are great. The dialogue is great. It's all just great. Yay for Dexter!