well it works fine for me, i use it for ordinary videos, for dvd's i use cyberlink power dvd, it came with my laptop. i personally really like quicktime, it is good.
unfortunately my cheap digital camera records short movies in AVI so that sux but for $90 in NZ that keeps me happy, till i get something with a screen to see the images that i took!!!! this one doesnt have one lol!
Most programs have some advantages, but in this case Quicktime has far many more disadvantages then advantages. Windows Media Player is far more advanced then it.