There's no comparison; Infinity is WAY more difficult to learn. While Dark Age does have a ton of special rules they are almost all very easy to remember after a game or two. Movement, combat, and cover are all very easy to learn. Target numbers are easy to figure out quickly (there aren't that many modifiers in the game.)
I'd suggest downloading the quick start rules here
http://www.dark-age.com/Downloads/QuickStart/QuickStartRules_4Sept2011.pdf. These 6 pages pretty much cover all the basics. You can also download the force lists, templates, and spells/effects for each faction so you can proxy a few models and try things out (you just won't be able to use the special abilities since they're only listed in the force list book.)