Your MMO must convince me that it is worth playing in less time than it takes me to download the next one. If your tutorial/introduction does not include heavy doses of awesome, soon, you will not be getting my credit card information. If you cannot bother to make the game look good in the one bit that you know every single player will see, I must assume that the rest of the game is worse.
Warhammer does this very well. Tutorial? More or less none; proceed straight to the war. You start on a battlefield. I started as a Greenskin, which is probably why I bought the game. Take a few steps forward from the log-in spot, and you can see dwarves attacking. The Dwarf area is much the same, with squigs and goblins running around the cave next door and giant cannons pointed at the enemy. NPCs are blasting each other in case you did not get the idea. The elf pairing has the gentlest, and therefore worst, introduction. Your starting spot feels safe, and your first enemies are tiny fairies. Even there, you have attacking forces 10 seconds away, and the good guys get to shoot down harpies with a ballista. Win.
The Lord of the Rings Online™ does this pretty well. The opening is pretty tame, but it immediately tosses in the things you want from Lord of the Rings. If you are a hobbit, you immediately see a Black Rider. Dwarves start next to Gandalf in a scene referenced in The Hobbit, and they proceed to a troll fight. Elves get a troll too, and humans and elves both start with the world burning down around them. It is not a great, action-packed intro, but it gives you the setting while you get your bearings.
City of Heroes is a mixed bag. Outbreak is very weak, notably the “run in a straight line” bits. Breakout is better, with a more interesting map and a mass NPC slugfest. The real awesomeness of City of Heroes, however, is the costume designer. Even before you put your character in the world, you pick from a mess of powers, see the cool toys that lie in wait, and then probably spend a ridiculous amount of time playing with paper dolls. That kind of thing makes the slow start of actual gameplay tolerable.
Many other games do it badly. I don’t even bother to mention most that I try. They were not worth the time to download, even if I downloaded while I slept. That thread has a bit of hate for Age of Conan, but they had the presence of mind to make the 1-20 game one of the most celebrated bits of content around.
Anyone want to comment on WoW’s opening? I tried a few way back in beta. The Undead was the most impressive. Dwarves were kind of meh.