I ended up watching '500 Days of Summer' the other day. After checking my testes at the door, it actually wasn't that bad.
For a great review of how much of a beta the main male lead is, Heartiste has a discussion here.
I remember a friend of mine once telling me that the over-arching theme of all of Oscar Wilde's work was to treat the serious things lightly, and the light things seriously. All the rest of the humour flowed from there. This helped me understand his work a lot more, but did spoil some of the surprise of it somewhat.
In the same vein, the twist to 500 Days of Summer is that they take stereotypical real-life (not movie-life) behavior of men and women , but reverse the sexes of the main characters.
(Some plot spoilers below the jump, but none that I think will impact your enjoyment of the movie).
So Tom (played by Joseph Gorden-Levitt) is a romantic who believes in 'the one' perfect girl. He's nervous about asking out the girl, and has to be pursued by her, making very few active moves to pursue her. He's constantly going to his circle of male friends for romantic advice about what to do (indeed, these characters serve no other role than as sounding boards for his indecision, and I can't recall any conversations they have with Tom that aren't about a girl. Almost like a reverse Bechdel test!).
Zooey Deschanel, by contrast, plays an essentially male character, Summer. She tells Tom straight away that she doesn't believe in love, and doesn't want a relationship. Tom ends up going out with her anyway, accepting this caveat but hoping it will change, as women often do in their relationships with alpha males.
(As a side note, I find it humourous how the phrase 'I don't want a relationship' in this context, like in real life, can mean at least two unrelated ideas:
1. I will not be emotionally involved to the extent that you likely will want.
2. I anticipate that other penises will enter my vagina during the period in which we go out.
Obviously there's no need at all to clarify exactly which of these two non-exclusive options she has in mind! Why would anyone care about that distinction?)
As I said, the behavior of Summer as an alpha-male is mirroring real-life behavior (i.e. this is how alphas actually behave), not romantic comedy conventions, where the alpha-male eventually wants nothing more than to commit to the female lead, after the requisite amount of dramatic tension.
The second-last part of the movie has Summer delivering to Tom the ultimate crushing blow that men deliver to women after relationships, but the women only see in hindsight: I told you I couldn't commit, but actually I just couldn't commit to you. Ouch. This is what makes the movie more interesting than the average rom-com (I know, how could it exceed that lofty standard?) - not-very-admirable male behavior is delivered by a female character that female audience members are generally meant to sympathise with. Hence the interesting dissonance of it all. If you want to see the best scene in the movie, it's a side-by-side comparison at the party of Tom's romantic expectations crashing with reality, viewable here.)
In case you're surmising a high level of powers of perception in my identifying the 'gender reversal of characters' shtick, they do flag it fairly explicitly in the movie - at the start, one of the male agony-aunt friends declares that Summer 'is a dude!' when she says she doesn't believe in love, while when she claims that they've been fighting like Sid and Nancy, she says that' she's Sid.
But this ended up having one unintended side-effect - because Summer played an essentially male character, she ended up failing to credibly portray the female ingenue that she was set up to be. To wit, I found her character to be flighty and annoying, rather than charming. Given that Zooey Deschanel plays a very similar character in all her work, you can contrast this with her character in 'The New Girl', who is superficially similar but more ... sweet, and good-natured, I guess. Which are ultimately idealised traits of female characters.
This is why her character on 'The New Girl' actually does do a good job of playing the eternal ingenue that every man wants. In 500 Days of Summer, they have to tell you via voiceover that Summer is the girl that every guys wants. They have to tell you this, because otherwise it wouldn't actually be obvious. Message: I Care.
Still, they do the best job they can of getting around this problem. And it's worth it, because without this twist, there wouldn't be much that's interesting about the movie. That sounds like a big indictment, but it's not - Oscar Wilde really did write great work. Obviously, this ain't Oscar Wilde, but it ain't too bad either.