Taken from Centralistic:
The idea of having external applications integrated into a centralistic closed system is quite interesting. Still having all of those applications decentralized with an open interchange protocol is much better, as Twitter has shown by now. Even Facebook with its custom server infrastructure and tailored software for scalability is doing tricks to reduce the load: By default FB only shows you status updates of 250 of your friends. If you have more, they are simply ignored. You can raise that limit for yourself in "Most Recent/Edit Options" but hardly anyone does that. Delivering each update to each intended recipient apparently is too hard to do, so people and advertisers resort to tricks to achieve that, like tagging all recipients in a flyer photograph.
- Comes with a chat function with funny toolbar usability as it is neither a proper webchat nor an external client application.
- No encrypted communications
- Close to zero privacy, and then it is also shared with external app developers
Facebook client interface
Facebook has a protocol for external clients, which sometimes works, and sometimes doesn't. That's when the funny behaviour of people logging in and out all the time is most obvious. You don't expect that from your IM client. They have replaced their custom protocol with XMPP by now. Strange, it seemed to be more stable before.