Yes please.
WoW is without a doubt the preeminent MMORPG on the market with somewhere around 11 million players worldwide. If you don't like WoW now, then this expansion will do nothing to change your mind. However if you are a WoW-head that has played to level 70 a couple of times and run out of things to do, then this is exactly what you've been hoping for.

Basically Wrath of the Lich King raises the level cap to 80, and gives players a whole new continent to explore. It includes all new quests, gear, spells that you would expect and a new profession called Inscription. Not to mention the ultimately cool new class the Death Knight, (with the small precondition that you have a level 55 character on your particular realm).

I love the new Death Knight quest line, as it gives players a new perspective on the WoW world. Playing as a servant of the Lich King, you get to raze a village, torture innocent villagers, and basically terrorize the countryside. As a matter of fact, most of the new quests from 70-80 have interesting twists that breathe new life into the leveling process.

Blizzard has always set the standard for excellent expansions, and WotLK is no exception. Somehow, the devs never run out of fresh new ideas, and they manage to add little touches that improve the gameplay in significant ways. Oftentimes they make changes that are so intuitive that you wonder why they weren't included from day one.

Bottom line: if you love WoW then then you probably already own this expansion and are racing toward level 80 as I type this. If not then you probably hate this game and think the graphics are cartoony, and the gameplay too casual. I love Blizzard, and have never been disappointed in the quality of their games, and I will be very busy for the next few months playing this new addition to the Blizzard library.