The visual effects are phenomenal and the lighting of the scene in the background on the Menu screen is an oversaturated style that looks like artwork, but surprisingly, is actually a model of your Armored Core. I was dumbfounded the first time I hit the button that rotates the camera when on the Menu screen and got the same reaction from J.R. Nip when I showed it to him.
The customization options have been reworked, and you now have more camouflage options to select as well as a really cool "template" system which allows you to plaster decals on your AC similar to vinyl graphics for cars. You can't create your own graphics from scratch, but you can combine several designs from a wide selection provided in the game, setting the color of each one, then layering them to create your own design. These decals can then be scaled and resized and applied to the different components of your AC, allowing for completely custom looks. Tweakers like myself are likely to spend a good bit of time in this editor.
In-game, the general feel of the series is maintained, but a new slickness and polish is readily apparent. First of all, everything looks better, with upgraded graphics and special effects. Also, there is a new target camera that will appear in the upper left corner of the H.U.D. when you target an enemy, a la Chromehounds. It's also important to pay attention to your H.U.D. in the various missions, though, because some missions feature additional maps of the area or other information useful to the mission. This is more the exception than the rule, but be watching for it.
The sound effects are well done, as is the voice acting, although some of the more frequently re-used phrases get a bit cliche'. Also interesting are the FMV scenes that take an artistic, cinematic approach at setting the stage via a narrative.