The standard raid frame is good, but not good enough. For example, it does not show who got agro, or which target a player has, or if the player is out of range. Therefore it is good to use an addon that does this if you have any use of this kind of information.
There are many replacments, for example Grid (the biggest), CT-raid (old), Vuhdo and more. I have started to use Vuhdo as I think that it is too much work to setup Grid. Vuhdo works well out of the box, and can do plenty of things. I use it as a raidleader to get a good overview of the state of the raid; like amount of health and mana, who got agro, if we need to take a mana break (or if I can continue to pull). When I’m healing (with my druid) I use it for click to cast, like healbot, but without needing to have healbot installed, it then shows me the duration of my hots, and other useful information.
Here is some more information:
http://www.hotsdots.com/tag/vuhdo/
