I remember they were making a big deal out of upgrading the servers.
A given server would be down for 24 hours, but thereafter was much improved.

At the start of Burning Crusade, queues could be as much as two hours but that was atypical.
Half an hour, was fairly common but sometimes there wouldn't be a queue.

After they took our server down, and did their upgrades, the queues basically were nothing.
Or if there were queues, they were rather minimal.



With WotLK, there were occasionally very short queues, but nothing like during the launch of BC.
The servers went down frequently, but that happened with BC too, and likely will with Cataclysm.