Thomas Jogin rants on Real Player with his article "Real Obnoxious". The critique is quite unflattering and true.
"Unfortunately, playing video streams is only a very small aspect of what Real Player does; Real Player, most prominently, is a small bastard with inferiority complex and delusions of grandeur, not too different from Napoleon."
Man, the title for this entry is awful.
Anyway, a lot of comments on that little rant point out that the Mac OS X version of RealPlayer is, compared to the spyware-laden Windows one, fairly benign. It's still a shitty, unwieldy, non-standard app, but it's not as insidious and pervasive as that article makes it out to be for Windows.
I have it, but I still use it as infrequently as possible.
It's much worse on Windows. The OS X version is mild compared to it. Although, the OS X version still sucks.