S1E6:

Season 1: Episode 6: The Slutty Pumpkin

Now, we're very specifically in October of 2005.

Robin having a boyfriend at the beginning of the episode really moves Robin away from being Ted's love-interest and even further towards just being a member of the group, which since we know she's not going to marry Ted, it's a nice shift. It also re-establishes her as not being ready for a serious relationship, and in fact, being quite solitary considering that she can't even bring herself to share dessert with a guy she's dating, all of which should in theory keep Ted away from her.
And added to Ted's list of women is The Slutty Pumpkin. Timeline-wise, he meets her in October of 2001. Ted's Cinderella-type search for her brings him back away from Barney-type of hookups and towards a real relationship, which as far as the title of the show goes, is a good direction. In addition, future-Ted doesn't clarify that The Slutty Pumpkin isn't his future wife for once (though it will be later in about season 6).
Now as far as Barney, his escapades with women are actually still quite entertaining despite how many times I have watched this show. Perhaps it is because he is consistant in his personality. While he constantly pretends to be various personas to sleep with women, he never seems to try to convince himself that he is any different.
I also still find Lily and Marshall entertaining. Maybe it is because they are consistently the epitome of true love as far as the show goes. While there are some rough points later on, they always work things out and get back together.
Focusing on Ted for a minute, his whole point in this episode is having faith regardless of the likelihood, waiting for The Slutty Pumpkin for the fourth year in a row despite that in all likelihood, she would not show up. It's this optimism that makes Ted a good protagonist, because it makes him likable. Interestingly enough, he has a romantic hopefulness as Gatsby does in The Great Gatsby. In both cases, the protagonists are focused on women who have moved on, and until they can move on, they are stuck (although in Gatsby's case, he can't move on). Maybe that's why Ted relapsing with Robin frustrates me so, even when the two end up on the roof together at the end of the episode because in the very first episode the audience is informed that Ted doesn't end up with Robin, and the him of the time can't see it, as much as they're ideologically opposed. But at the end of this episode, Ted is still the optimist.