sloganvirst: What is XNA? I am not that worried about what platform it is on either...
What are the graphics like?
It's a Microsoft framework for game development using .NET. It's free to use and is targeted at indie developers. There are a lot of resources and examples available online. (Ugh, I'm sounding like a Microsoft ad - I'm not) It's good for both 2D and 3D stuff - Terraria, Magicka and Sol Survivor are written in it.
Here's a pre-alpha screenshot from a game I'm working on. The above was made completely by myself and one other student (there were two other guys involved but they didn't do any programming or art, so they didn't directly contribute to what you see there). We did it in the space of a couple of weeks, while we each had three other subjects to worry about. It was our first time using XNA. We had animation, gravity, shooting, object/person interaction, collision detection and heightmapped terrain working as well, but they're not really apparent in the pic.
It doesn't look fantastic due to time constraints, but it looks better now. Unfortunately I couldn't get a proper screenshot because we have all this debug stuff visible like bounding boxes etc.
Basically, you're limited by your artistic and programming skills as to what it looks like, as well as how quickly you want to make it. We're using C#, but I believe you can use visual basic and C++ as well. You won't be able to make something as powerful or fast as say, UE3, but you make up for that in ease of development and the ability to customise it as far as your imagination allows.
I highly recommend it if you want to achieve stuff quickly. You do need to code everything yourself though, it's not just scripting.