I got MGS3D as well, and this is the first MGS game I've ever played.
For the record, the graphics are just gorgeous, and would even agree with EDGE that it looks better than the HD versions because, graphically, it isn't just a simple port. It may not have increased resolution and improved textures like the HD version has, but it uses the 3DS's shaders and such that the HD versions do not include, making the presentation a great one in it's own regard. However, it isn't without the simple fact that the frame rate dips into the 20s and sometimes even lower, but the only times I've seen that happen are during cutscenes, which imo isn't really problematic. The framerate during gameplay looks to be rather steady from the areas I've experienced.