Make no mistake: Early Cataclysm dungeons are not the faceroll that we experienced at the end of Wrath. Not only have everyone's gear levels dropped dramatically relative to the content, but Blizzard has returned to a more BC-style design philosophy wherein crowd control really matters and one live mob can make the difference between an easy pull and a very difficult one.
Of course, the ideal solution is to read up on the dungeons beforehand and make sure you're prepared for them, but we don't live in an ideal world. Sometimes, you'll wind up in a random dungeon that you weren't expecting, and you haven't had time to research. Additionally, dungeon guides don't always give tips for trash, and trash pulls now require some coordination. Luckily, instance design does not expect you to have an encyclopedia in your head. An alert dungeoneer can succeed on the fly by following a few simple tips.