I was referring primarily to the screen sharing features of the aforementioned services. In general, they're barely adequate for slideshow presentations, but the transitions are still going to be rough. And even when everybody in the virtual conference has a solid internet connection, the user experience is still a lot worse than when a PDF of the slides is emailed out before the meeting starts.

I find it simply amazing that all these "collaboration" tools aspire to little more than emulating the use-cases of broadcast television or a large lecture hall, and there a so few tools that try to enhance the experience in ways that are only possible when every participant has their own screen and computer.