As per this article http://ps3.ign.com/articles/944/944857p1.html?RSSwhen2009-01-14_045700&RSSid=944857
"The cover system isn't quite so forgiving as Gears' and if you duck behind a low barricade you'll still expose yourself to fire, meaning you've got to choose your resting points carefully, especially when Helghast troops are clever enough to attempt to outflank you."
It seems like its a more realistic cover system.
That's not a correct statement. Depending on your position, you can shoot someone behind cover in Gears also, even if their cover is facing you.
@Munkeh-Fair enough, but it would be nice to leave it in and let the community decide whether they wanted to quicken the pace or not.