There are a couple overall themes with Dean this ep, but mostly the meta to be found is bits and pieces of Dean. For instance, Dean sniff-checks his clothes, for laundering. Heeeheeheeeee. Ahem.
Dean tells Sam that he's "the one who's been with him every day for two years" when Sam accuses him of not caring about finding their dad. Now, this can't be taken as strictly factual, as Sam was gone to college four years, and Dean has been on solo hunts since Sam left. Even if he wasn't on a lot of solo hunts, he was on enough that, as of the pilot, Dean hadn't seen their dad for three weeks -- if it takes three weeks and a voice mail for Dean to freak out enough to start looking, then it implies that Dean and dad have been apart for periods of time, before, of at least 2-3 week lengths.
But his point is made that, while Sam was having nothing to do with them, Dean was with dad. At this point I don't have more conclusions to draw about this, but in later eps, we can use this to look at the role Dean's family plays in his life. For now we just take note of the fact that, as an adult, Dean spends his time with dad, and on dad's mission of choice - hunting evil things.
Dean says "watching one of your parents die isn't something you just get over." Now, given the flashbacks, I don't think wee!Dean saw his mother actually die, but I could be wrong. But he saw into the room where she was burning, and maybe even saw Sam's crib on fire. So he saw the time and place - just possibly not her actual dead body. But to a four year old, the nitpick probably doesn't matter. He saw her die, he never got over it.
Also of note, when he draws a picture of his family for Lucas, he includes his mom. He tells Lucas that he thinks about her, and her wanting him to be brave, every day. When Sam says Dean never told him about that stuff, Dean says it's no big deal - and his tone is calm. He's obviously repressing his emotions here, but he doesn't come across as denying them. He sneers and whines at the idea of having to hug, showing us that Dean doesn't want to indulge in his emotions with Sam. But that isn't necessarily the same thing as denying them.
I suspect Dean feels them, a lot, and understands his emotions. He just doesn't like dragging them out to be looked at and pawed over. When he needs to connect with someone else, in order to help them, he does admit, if not freely, then at least readily, that he has these emotions.
Dean shows every sign of having dealt with his mom's death, in that he remembers her, incorporates her into his life in terms of 'this is what she would want, this is what she'd believe.' He doesn't seem to hesitate as he draws her into his family portrait. And his comments to and about Lucas don't come across as forced, or couched in order to elicit response from Lucas. He isn't 'playing up' his mother's death in order to make Lucas trust him.
Despite the pain and trauma Dean has suffered, in this episode he comes across as a fairly well adjusted, emotionally healthy person. He might not be as emotionally expressive as he could be, but he doesn't strike me as unhealthily repressed, either. His mother's death still causes him pain, but he isn't suffering over it -- he isn't tortured and obsessed, like some people we could name if we could jump ahead a few episodes. ;-)
If you also take into account that Dean readily and happily flirts with the waitress -- to the point he'll stop angsting over dad being missing in order to watch her butt as she walks by -- he seems pretty un-tormented by his life.
And Dean is so, so pretty.