US Test Realms Open!
The Test Realms came online either late Friday night or early Saturday morning, depending on how you'd rather look at it, and already stability problems abound. Last night I was unable to get past the character selection screen (getting repeatedly disconnected at various stages of login) and I am currently waiting in a queue of nearly a thousand people. Estimated wait time? 62 minutes. I'm hoping this is just a sign of immense overcrowding...
However, the test server is a great way to look at and try out changes Blizzard has made in the latest patch, and offer your feedback in the Test Realm forum. Blizzard will let you transfer characters to the realm - a service which is oddly only available between 3AM and 3PM Monday through Friday, but until then, there are sample characters you can copy and try out - but be warned, you're only allowed two copies, and these count against them). To get started, download the appropriate test client and then click on Public Test in the lower left of the start-up screen.
