A game is better when it has a clean, self-evident user interface. It's better when the only time you don't understand something, it's an intentional mystery put in by the game designers. Blizzard has done two things in Cataclysm to really help with that.
One is to clean up the ability tooltips. They used to include very precise numbers about healing or damage down that were completely inaccurate, because they didn't include buffs. The tooltip would say heals for 1021, and the actual heal would be more like 5000. In Cataclysm, they've removed the numbers and instead they say things like "heals for a large amount". Additionally, they've added a sentence to the most important abilities to say when you should use them. For example, "Use this on a player whose health is very low".
A second way is the inclusion of much of wowhead into the game. Already they include a quest helper, meaning crucial locations for quests show up right on the map. In 4.2 they are adding the Dungeon Journal, so it won't be necessary to go to wowhead just to remember which abilities this particular boss has.
Some people are complaining that these changes make the game too easy, but that's a crude way to look at them. The things that are being made easy are things that should have been easy to begin with. They are the basic game mechanics. Count me in as not wanting to have to go to a separate resource to figure out basics of the game. That's wonderful that the Internet allows such information sources to gather, but I'd rather the game designers put the information into the game to begin with.