So, the old world is going to be revamped in only a few days it seems. No additional character slots in sight, so I won't be making any new alts on my home servers, but I guess nothing stops me from making a troll druid, a tauren paladin or whatever on another server. They won't have access to heirlooms of course... but I'm starting to think that this is probably be a good thing.
Of the alts that I've been levelling recently, two have both heirloom shoulders and the chest to boost experience gains, one has shoulders only and two went entirely without any heirlooms. I think it's great that these items exist to give people the option of shortening their time spent levelling, but as someone who actually enjoys levelling I'm becoming more and more convinced that I'm actually better off without them.
How fast is too fast?
Faster levelling doesn't have to be a bad thing even if you do like the levelling process - after all everyone has zones and levelling ranges that they don't like as much and where they'd rather move on to something else sooner than later. In fact, at first I enjoyed the freedom of picking and choosing my favourite quests and zones on my heirloomed alts, but it soon became apparent that I advanced so quickly that I unintentionally ended up leaving content that I really liked behind as well. For example it felt rather awkward on my rogue when I realised that all the mobs in the Arathi Highlands had gone grey before I had even had an opportunity to get started on the zone, and I nearly missed my chance at gainful questing in Tanaris as well, even though I love doing the wastewanderer and pirate quests there.
It was even funnier when I quested in Silverpine Forest with my fully heirloomed mage. Silverpine used to be the worst of the 10-20 zones for the Horde because quests were so scarce that you couldn't really make it through the zone's level range without doing something else on the side as well... but on my mage I gained a full ten levels in Silverpine alone, with the last quests having gone grey by the time I got around to them. Overkill, thy name is restedness plus heirlooms.
In comparison the pace at which my Alliance hunter advanced through Redridge and Darkshire, with no heirlooms and not always rested, felt much more natural and "right". Considering that the revamped low-level questing is supposed to be so awesome that I'll want to see all of it and multiple times, I really see no reason to make my next bunch of alts rush to eighty(-five).
She who has everything misses out on a lot of upgrades
Another supposed advantage of heirlooms is that they scale with your character's progress, meaning that you'll always have the equivalent of a blue quality item of your level equipped in your heirloom slot and will never have to worry about upgrades. This is particularly nice for melee classes, who are heavily dependent on their weapons for good damage output. If you've ever outlevelled your gear by ten levels or more without noticing it immediately, you'll know what that's like.
On the flip side however, half the dungeon drops and quest rewards that you'll see on your way to max level will be completely useless to you. This didn't seem like that much of a problem to me in theory, after all I still had plenty of other gear slots... but as it turned out, the vast majority of instance drops seem to be things like weapons and chest pieces. I actually found this quite depressing on my rogue after a while, seeing yet another dagger or sword drop and going: "Oh, rogue weapon! Oh wait, I got the heirlooms..." There's something very fun about receiving gear upgrades, and being "stuck" with the same chest, shoulders, weapons and whatever other heirlooms you may have is actually kind of sad and a bit of a fun-sucker. Which leads us to the third point:
Looks do matter
I don't know about you, but the first time I got heirloom shoulders for one of my low-level alts they felt extremely cool. Usually you wouldn't get any shoulders at all until around level twenty, but the heirlooms can be worn from level one. Likewise all the other heirlooms borrow their looks from old level sixty gear and thus look a lot shinier than anything else a low-level character would usually wear.
The problem is, this gets old really fast. Again my mage was the most striking example. When I bought him the heirloom cloth shoulders, robe and caster staff in his teens, he went from looking like a ragged farmboy to a truly mighty mage. This was cool for about five minutes, until I started running into other people in the zone I was questing in and every other mage, warlock or priest looked exactly like me. That's beyond a fashion faux-pas, that's a disaster. And I mean, it's not as if you just happen to look the same for a few levels like people often do in Hellfire Peninsula, you'll look exactly the same for the entirety of your levelling process. How sucky is that? I'm not expecting to be a unique snowflake all the time, but levelling the 147th clone trooper is no fun either.
In summary, I don't think I'll be interested in buying any of the new heirlooms in Cataclysm, but I'll keep using the ones that I already have on the characters that have been using them for a while, because once you start using them it's kind of annoying to go back to normal gear, as you might not happen to have an appropriate chest, shoulders and weapon lying around to replace them...