Wrath of the Lich King has an extremely flat leveling curve, you only need 10% more xp to level from 79 to 80 than it took from 70 to 71. As the xp for quests and monster kills rise somewhat faster than that per level, leveling up gets actually *faster* the closer you approach 80.
My priest is level 78, and just started questing in Storm Peaks. I'll probably reach level 80 this weekend. Just by regular questing you easily make 300 kXP per hour, and as one level only takes between 1.5 and 1.7 million XP, it takes only 5 to 6 hours to level up, unless you are busy doing stuff that doesn't bring experience points. So I'll be 80 in less than 4 weeks after release, and that is still slow. Last night, according to WoWCensus, a third of all Horde players online on my server were already level 80. My guild is planning the first Naxx raid for Friday. Is leveling in Wrath of the Lich King too fast?
That question can only be answered with a counter-question: Too fast compared to what? It isn't too fast compared to the amount of leveling content offered. I'll probably hit 80 about the same time as I finish all the quests in Storm Peaks, which would be my 4th completed zone. So if I then play my next character from level 70 to 80, I can reach 80 by playing 4 completely different zones, and not do a single quest twice. Awesome! That is something I'm looking forward to.
What I'm not looking forward to is what to do once all my characters are 80. Yes, there will be heroics, raids, and other fun stuff to do. But after leveling to 80 in less than a month, chances are I'll be stuck for over 20 months *at* 80. So, compared to the time it takes Blizzard to release an expansion, that is to say the time you spend at the level cap, leveling *is* too fast. Even if I consider alts, I'll have seen all the zones and all the quests in two months, which is too short compared to a two-year expansion cycle. Blizzard would need to pull a rabbit out of their hat and release the next expansion in a year, but even the most ardent optimists don't believe in that one.
But then many people seem to enjoy fast leveling. With the reduced xp to level up to 70 now, you can create a level 1 character in World of Warcraft and level him to 80 faster than you can create a level 1 character in Warhammer Online and level him to 40. With a "the game begins at the level cap" attitude, faster leveling is better. But then, if leveling is just an obstacle on the way to the cap, why do we need it at all? Why not make a game like Guild Wars, where you can immediately create a max level character? I think in their haste to level up, a lot of people are missing a major fun part of the game. For me personally, leveling a bit slower would have been fine.