I played around in Northrend for a while and was reasonably happy. It feels more like a real place (if you know what I mean) than the Outlands which always felt like an asteroid floating in space. That was good fun to jump off though. Dropped about 200 gold in the first 2 minutes buying up all the grand master skills, though.
The initial quests actually seemed very reminiscent of the starter quests for levels 1-5, I thought. Vengeance Landing feels like a noob zone despite the war going on. I suppose it's for everyone whose got out of the habit of levelling. Speaking of which, I noticed that there were level 74 death knights running around 18 hours after the release. Way to go guys. There's a feeling in some quarters that Blizzard really ought to have an 'I Have No Life' achievement for the first person to hit the level cap, but I think that first anything is actually pretty cool.
One difference that I noticed was that the levelling truce that seemed to be in force in the early days of the Burning Crusade was off. We got ganked and corpse camped by the allies whilst looking around Utgard Keep. Ah well, onward and upward.