Ok. One of the hardest things to get when setting up a party for DM west, it's to find someone who can open the door. A rogue is not always available and most people don't care about getting a key to an old pointless instance. BE PREPARED. Get that key. As a pretty poorly geared demolock (well, 3 pieces of gladiator gear, but still not enough spell damage to be accepted into heroic runs) I soloed the DM east wing (well, not the full wing, but enough of it to corner that imp Pusillin who drops it, and to kill him and his buddies. Be careful though, he reflects spells back to you, wand him). This was after I got the steed though, but I decided to have it in my inventory in case I'd see a warlock in need.
So when you have the key, all you need is a group. Well with a party 3 warlocks (lvl 70, lvl 69 and lvl 64), a lvl 62 tank and a lvl 70 pally healer, we did it with no problems. Have a competent and sympathetic group though, otherwise you won't even make it to Immolthar. With a good party though, you'll have the dreadsteed at 10% before the dreadlord even spawns.
As for the steed itself, it's a beautiful mount, looks cool, the armor plates even glimmer under the sun. The only downside of it in my opinion is the huge horns growing out of it's shoulders, disproportionate, and ugly. But well, a perfect mount does not exist. Apart from that, a very cool looking mount.
1. Yes, I own a Dreadsteed and it is worth it in my opinion.
2. Yes, there is some prestige in owning a Dreadsteed and it's really THE symbol of an accomplished 'lock. After all, as they say, "What's a warlock without his mount"?*
But I don't look down on people not having one, I know it's hard, can really get on your nerves, and furthermore there's almost nobody to look down at... 99.99% of 'locks on my server have a Dreadsteed.
*A walking warlock. That's what my party said when I asked them the question.