Well i can type out a 10 pages post on this subject but i'm not planning to do that so i will keep it short
the vita version will look in comparison towards any ps3 uncharted, polygonal starving.
It will give the appeal of being uncharted for sure, through being able to push out complex shading etc much like the ps3 is capable of. but the amounts of it pushed even on a smaller screen is only going to contain so much.
If you look at any vita screenhots or video, you can clearly see that the vita version of uncharted will beat any uncharted on the ps3 on the following solutions:
textures textures textures.
If you look at screenshots of the vita version which are a tad bullshots, but oh well it probably gives that appearance on its screen, is that the textures are sharp really sharp and clear. This is something that the ps3 is unable to push out. the oled screen is going to project them nicely even on top of it.
another thing that the vita seems to be good capable of is particle effects and it manages advanced shading solutions nicely without much of a sacrifice it seems.
The filtering on top of it on the screen 4x msaa ( which is incredible v-ram demanding ) is going to be a solid solution if it gets pushed if not, then 2x msaa will already give it a nice solution over the ps3 versions really no matter if the ps3 does the same kind of filtering, it will always look superior on its vita solution.
The big downsizes and which will always be the case are the following:
Polygons / complexity of shading "more limited amounts of shading" like dynamic lights + self shadowing + multiple layers of texture rendering etc. It will eat performance and probably wont be used that often on a really deep volume because of it.
Another problem really hits with it ( even while this isn't asked ) that the vita will always camp with a budgets instead of aaa budgets, and mostly gets shafted with teams that normally do not go the whole mile as it isn't there game to start with ( in other words b teams , or other teams ).
Anyway to answer your question:
Yes the vita is able to beat the PS3 uncharted 3 game on: filtering,texturing, on its own screen.
No the vita isn't ever going to beat a PS3 uncharted 3 game on: complexity, polygonal solutions, and shading solutions.
at the end of the vita lifetime i'm sure we will see efforts that are top notch ps3 solutions and even give a better result on the vita, but the "no" parts clearly represents stuff that the vita will always be limited with what it has on hardware base and never can break free from it to jump towards the next level ( which it ofcourse isn't builded for )
