QUOTE(Astron @ May 10 2013, 07:31)

As opposed to Don who is such a love-able sweetheart?

The difference is that Don owns his dick status. (No pun intended.) He is who he is, like it or not. Yes, he has a lot of self-loathing, but he isn't pathetic about it -- he doesn't, for instance, cheat on his wife and then get pissed off at her for finding out and being pissed off about it. That's a Pete move, not a Don one.
That's why I said that Peggy and Pete embody the best and worst of Don, respectively. In Pete's case, that means that he emulates Don, but he hates himself for doing so. He looks up to Don, but he doesn't know
why he looks up to Don, because every time that he tries to be more like Don, he just makes a mess of things and ends up hating himself more. I just can't respect a character who is that pathetic -- either own up to the bad choices that you're making, or
stop making them.
Peggy, on the other hand, took all of the business lessons that she learned from Don and put them to good use. The Heinz thing was a direct page out of Don's book. In all fairness, Don should have thought of that pitch -- he's the one who taught it to Peggy, after all. But he's too disillusioned at this point to care about trying to woo the companies -- he feels like
he's the ad executive and these companies are telling
him how to do
his job, when they should really just be saying, "Your work speaks for itself, so whatever you want to do, we'll go with it." Meanwhile, Peggy is still young and optimistic, and she can't
expect respect like Don does, because she knows that she hasn't really done anything to earn it yet. That puts a fire under her ass that has long since stopped burning under Don's ass. Meanwhile, she's now starting to flirt with the idea of infidelity -- another thing that she learned from Don. My guess is that she'll prove to be better at that than Pete is, too.
I don't understand why you're asserting that Don wasn't really important in the most recent episode. They lost Jaguar because of him. They merged because of him. He was the driving force behind everything that happened in that episode.
He's unhappy because he's unhappy -- that's kind of the point, IMO. He tried to change his life -- he got a gorgeous new wife, and I think that he genuinely believed for a while that he was going to be happy with her...but eventually, he realized that he still wasn't, and he doesn't know why, which makes him unhappy. (In other words, if he knew
why he was unhappy, he could change it, but he doesn't, and that's why he's unhappy -- because he can't change his unhappiness.) When Don is unhappy, he goes looking for that elusive happiness elsewhere -- like in the arms of a friend's wife -- but that's not a happiness that he can hold on to for any significant period of time, so it's a vicious cycle for him.