Yes, of course it's more of the same. But it's more of the same great stuff.

User Rating: 9.5 | World of Warcraft: Wrath of the Lich King PC
Yes, WoW is old, over 4 years old now. Of course this latest expansion is more of the same. What are they going to do, create an entire new engine to run the game on when there's 11.5 million people subscribing to the one they have? If you didn't like it 4 years ago, you won't like it now. But if you're like 99% of the people who've tried it, you were hooked within the first 5 minutes. Maybe even 5 seconds, like I was. Maybe you've even swayed away from the game and quit playing for a year at some point over those 4 years, like I did. But the same thing will always hold true for World of Warcraft: if you enjoyed it then, you'll enjoy it now. And if you've never tried the game, there's no better time than now, and I think the popularity of this game speaks for itself that this is a game you don't want to NOT try.
All that being said, the latest expansion Wrath of the Lich King does 2 major things for the game. The first is increasing the level cap to 80 and providing a new continent to reach that level, Northrend. The second is introducing the new class, the Death Knight. Northrend is filled with new zones full of quests you've probably seen before, I.E. go gather X or go kill Y. There's also some you haven't seen, like one where you gain control of a Steam Tank and lay waste to some scourge using a pop-up interface unique to that vehicle. The new zones are wonderfully designed, just like the rest of the hugely beautiful world of Warcraft.
The Death Knight is overpowered right now. The class, instead of using energy or mana, uses Runes. There are 3 different runes, blood, frost, and unholy. Each of these 3 types of runes acts almost like it's own energy ticker, similar to a rogues abilities. An ability will cost "1 blood rune" or "2 frost runes", and then that specific rune will have to re-charge before you can use another ability from that rune's tree. The 3 talent trees, also blood, frost, and unholy, are invested in to steer your Death Knight towards one or more of the runes you want to be the most powerful. These separate runes' abilities can all be used independently of each other and in rapid succession, making the Death Knight capable of high sustained DPS as well as high burst damage. Not to mention the wearing of plate armor makes the DK a very viable tank if needed, as well.
The bottom line for WotLK is the same as it was for The Burning Crusade: If you like WoW, you like WoW, and you should play it. If you don't like WoW, you're nuts, so let us who do enjoy it be and I wish you good luck in finding a better game.