I think OpenID has proven to be uneffective, some (HN popular) sites have removed it again (37signals? not sure).

I have problems with OpenID, too, because I tend to be unable to remember which OpenID login I used for a site.

Why do you use more than one? I thought the point was that you could sign in once with your OpenID and be signed in everywhere.

It just happened, I was a little bit careless and used both Yahoo and Google. I don't remember the exact problems anymore - I think also if the web site does not link directly to the OpenID provider it is hard to fill in the details.

Or maybe it was that Yahoo creates several OpenID logins?

Unfortunately, the prevailing sentiment right now seems to be that OpenID is not a good idea.

Why, exactly? I'm about 100x more likely to sign up for your site if you let me press a button and log in with my Google account. It's also really easy to implement with Django middleware.

Google turns up a Quora thing which, frankly, is full of handwaving bullshit.

Are there actual technical reasons why OpenID is bad?

I wasn't talking about whether I thought it was good or bad, just that it seems to me like most people on HN usually look down on it.

And the reasons are mostly ones of user-friendliness (not technical reasons). I've heard of plenty of people who still never signed up for StackOverflow because it requires OpenID.

As far as I understand it, OpenID is still used, for letting people login with Google or even Yahoo accounts, but no longer with full flexibility in OpenID providers.

OpenID is ridiculously complex for what it does (and in any case, complexity is the antithesis of security), and fortunately seems to have failed.

The abstract idea was good, the standard itself is awful.

Actually, I would say that for the average user, a well done OpenID login is considerably less complex precisely because they don't need to make up another username/password to memorize or otherwise keep track of.

You need look no further than any of the stackoverflow related sites to see a very successful large scale site using OpenID.

I'd also suggest looking at tripit.com, catch.com, mindmeister.com or springnote.com to see excellent examples of OpenID login done in a way that's very user friendly while also providing the option of a traditional login for people who prefer it.