I have been pretty negative on the storytelling aspect of Vanilla and Burning Crusade, mainly because the catching and compelling storylines have been far and between. The few lines in Vanilla (Missing Diplomat, or the Darrowshire Heroes questline for example) are just remarkably good story telling, both taking you along as the 'hero', or at least creating the illusion.
Burning Crusade follows the same rule: sometimes you feel like part of the story, but there is no real storyline to follow. And the areas are pretty much separated one from another, with as much connection in between them as there is connection in their visual styles. Like Lodur said:
The terrain didn’t blend very well between zones. Good example would be going from Zangarmarsh to Nagrand, the contrast was incredibly violent. This theme persisted through most of the between zone areasI quite undersign that. Also, levelling now, way behind the main wave of players, the reputation grind is pointless: at the point when you start to gain benefits from the rewards (or are in a position to get them) you are headlong in the Northrend already, wondering how to get that Scryer shoulder enchant easier...
To the word of the day: levelling game in The Wrath of the Lich King. The short version is that the levelling speed was too fast, levelling was too easy and the quests pretty repetitive with few very nice sideshows on the road. Longer version: let's break the short one into pieces.
Like I stated earlier, I levelled for the first time and way behind the main population. This causes the illusion that you are levelling alone or in the best case with just few people around. This makes grouping a pain in the behind, too, but that seems to be common problem persisting till the level cap (and not getting any easier even then, either).
The entry to Northrend is shocking: after the tranquil and almost solemn Outlands you enter into a warzone: where a certain *other* MMO claimed that the War is Everywhere, it surely feels like that when you set your foot on the continent! In Borean Tundra -where I landed first- you are confronted with Nerubians fighting to push the human contigent in to the ocean (and end up saving their day), in Howling Fjord you are put against the raving Vrykul's and their bloodrage. In both places the quests are pretty standard, not too involving but usually continuing onwards. This was a change in the pace: you didn't get single shots, nor the 'best' quest rewards from the first quest. The gear reward came only after completing the quests on the questgiver, which actually showed you easily when the quests got finished! Great thinking in continuity wise.
The levelling speed increased greatly, in my case most likely due to the fact that I got myself involved with the stories. I just had to kick the green viking's butt for the Kaluak's (gaining reputation enough to get the sweet breastplate as early as possible), help the Explorers Guild to get into the bottom of things in Howling Fjord and so on. The questing in storylines compelled me to check the next phase. This caused even more profound problem: I over levelled the instances yet again. For a first timer this is a loss, for the gear reward from the instance quests and bosses are huge improvement to the gear achieved otherwise.Also the fact that the areas have dailies available from very early on increases the levelling speed, for the dailies are very easy quests with maximum exp reward, and in addition to questing you could easily do easy dailies every day without hindering your questing. Reputation grind while questing is an option, and a good one.
Even though the speed was increased mostly because I wanted to continue the book, the quests were overly simplified. At very early stage the protection warrior was downing mobs 2-3 levels higher, and with max rested bonus this means 2-2.5k per mob. Take ten "kill ten foozles"-quests and its reward and you're rocking. It was a kind of disappointment that the 'challenge' was off, but then again the experience in Utgarde Keep showed me that the challenge was in the instances. The disparity of these two is huge.
Needless to say, that the graphics are beautiful. But phasing still amazes me from time to time, as I encounter it while tying the lose ends of the quest chains. The first instances (Borean Tundra coastline) showed that it's a powerfull story telling device, Wrathgate proved that it combined with a strong story gets you very much involved in the story yourself and the Argent Vanguard and Shadow Vault quests show the power of the phasing in a way that the game makes you feel you are making a difference. I still cannot fly over the first without grinning, you know why if you have completed the Tiron Fordring's quests in the area. The effect is fantastic!
There are few sideshows which are worth the while and some which aren't. Granted that the D.E.T.H.A quests are nice and cuddly and all, but they serve no purpose in the overall content. Well, maybe they foreshadow the Hemet Nesingwary quests in the Sholazar Basin in a way, but otherwise they were IMO just a distraction. On the other hand, Nesingwary's quests -even though they were mainly killing and slaughtering as always- gave the feeling of accomplishment in a peculiar way. And no one can deny the power of distilling your own booze, for sure.
If there is one thing that bothered me all the way up in Northrend was the fact that the gear upgrades were pretty static and came at certain level ranges. You get seven similar pieces of gear with just slightly different stats to suit some specifications, which was enraging. The gear ups till -something like- lv75-76 were more or less cosmetic, at least looking from the world drop/quest reward side, but at that point the reward structure changed dramatically. Perhaps because at that point the first Honored faction rewards came into play, the rewards from quests had to be at about level with them. Inferior, but at level.
All in all, I levelled too fast and skipped several areas. But then again, the only areas that really matter are Dragonblight and Icecrown for obvious reasons, and everything else is just foreshadowing the incidents in those areas. If there is something I wish for in Cataclysm, it's that they bind the stories into as good and narrative packages as they did in the best ones in The Wrath of the Lich King. That will make the day for sure.