Im thinking of getting Myst masterpeice Ed. I was wondering if its similar graphically to myst 4? or if the prerender's are similar.

Since you've asked basically the same thing about two games and the answer is the same for both, I'll just answer you here.

Myst was originally released in 1993, and was the product of four guys working on their Macintoshes with incredibly early versions of the software programs that have since become the standard for these sorts of things (as well as a few that have vanished from the market since 1993). The images are nowhere near as detailed, or even as large, as the content in Revelation. There are no free-look nodes, just a strict slideshow environment. There are very few ambient animations, and the atmospheric effects are rudimentary at best in most places. I'm being blunt because I don't want you to get your hopes up for a game that looks just as awesome as Revelation does. If you want examples of what the images in this game look like, look here.

Myst III: Exile was released in 2001, so it looks light-years better than Myst does, but it was not produced to the same level of ambience that Revelation was. The free-look nodes were first implemented in this game, but again, the ambient animation is far less prevalent than it is in Revelation. There are pictures of Exile here for you to take a look at if you want.

That said, both games are still worth getting (as is Riven... especially Riven) for their story, their puzzles, and the fun of visiting more worlds in the Myst universe, even if they aren't as complex as the ones in Revelation.