Additional Information: There's supposed to be a Zepplin from Eversong to Undercity, so that lowbies can get in and out of the new horde zones at low levels. But I haven't found this yet to confirm. Standby on that.
What is there to do in Outland?
There are three new key things, in my opinion, that makes Outland appealing.
1. New lands to explore and experience.
2. New crafting formulae and trainers.
3. It's beautifully done
Before going into the Dark Portal, get any stuff you need from your bank. You won't have access to a bank there for a little while. Go down to the Blasted Lands and talk to the Alliance/Horde watch commander, and get the quest to enter the Dark Portal. On the other side there's the raging war between the Azerothians and the Burning Legion, but it's all being carried out by high level alliance/horde NPCs - not much you can do but enjoy the spectacle of the alliance and the horde working together to hold back the Burning Legion. Reminds of Mt Hyjal all over again, eh?
Finishing the quest attunes you so that you can take your first flight path from The Dark Portal/Legion Front to the first Outland town - Honor Hold for alliance, and Thrallmar for the horde. Dark Portal is a Sanctuary area - blue on your minimap. What does this mean? It means it's neither horde nor alliance, and it's a safe place to get away from things. At least... behind the front with the Legion, it is. It's also non-factional. There are other sanctuaries on Outland.
What do you do here? Well I'd suggest training up your professions! In under to increase your crafting skill from 300 to 375, you have to train as a Master of that trade. How? From the Grand Master. In Honor Hold/Thrallmar there are all the Grand Master trainers for your PRIMARY skills. Secondary crafts are trained elsewhere, except cooking - which should be in the inn, there in Honor Hold/Thrallmar. Primary crafts are trained from the Gran Masters, secondary skills are learned from books you buy. Train Master in your primary and cooking skills so you can increase skill again.
Hunters: Throw out all your old shoddy ammo. I don't care if it's Thorium, it's out of date. Crap. Obsolete. Sell it off. Now... there's a better way. Go to the General Goods vendor (or a Bowyer in Azerothian cities) and you'll find lvl 55 white arrows with 22 DPS! And that's not the least of it, my friend. You'll find even better ammo later on. FILL your quiver with Wicked Arrows and your on your way! Oh, by the way - no new Stable Slots. Why? Don't need 'em! To learn new pet skills, just fight a beast a few times and you learn it's skills, and then teach them to your own pet.
Once all your crafts are at 300/375, ready your weapon. There's a TON of quests. I mean... there's quests friggin EVERYWHERE. Oh, what's this? Quest log... 20/25?! Yes, that's right - there's room in your quest log because you can fit 25 quests now! You'll need them. Everywhere you turn in Outland, there's 50 new quests for you to do. Be VERY choosy which ones you get first.
Hellfire Penninsula is kinda like the Barrens - it's very long and full of mobs. That's why there's another, smaller town, on the far end of the zone with a connecting flight path. Oh, pick up the First Aid book while you're there. But don't forget Thrallmar/Honor Hold. Why? Their a new faction that, if you get rep with them, you get new reputation-based vendor rewards. There are a LOT of new factions to get reputation with in Outland.
But wait! What's this! Golems I can mine for ore! Yes... and Rich Thorium Nodes are like copper in a starting area here - they are EVERYwhere. And these Rich Thorium Nodes hit for 3-5 thorium a node. They are common as copper here. Occasionally - if your lucky - you'll find some Feliron nodes- one of the new metals you need to skill up on. Not only metals, there's Knothide Leather you can get skinning these mobs, and new herbs to skill up on. The humanoids drop Netherweave Cloth for Tailoring and First Aid.
Beyond Hellfire Penninsula is Zangarmarsh. It's a marshland forested by... giant mushrooms. This is actually lore, because in WC2x the 'trees' on Draenor were actually forests of mushrooms. Most were lost when Draenor exploded, but Zangarmarsh is being maintained by... someone. Your first stop is a neutral town built by... Night Elves? Huh? What are Night Elven buildings doing here? Well, back in WC3 an over-zealous warden named Maieve Shadowsong trailed Illidan to Outland in her quest for 'justice'. Well it seems an expedition of Cenarian druids (NE/Taurens) took up residence in this NE town. But they are not associated with the Cenarian Circle. Why? I don't know... yet. They are a new faction to do quests for and earn new reputation-based vendor rewards from. Pick up the fishing book while your here, learn Master Fishing, and cast your line.
In the marsh are LVL 62+ beasts and naga, as well as an alliance (Draenei) and horde (Belf) towns with flight paths. But take the time to venture south from here into the Terrokar forest, to the town right as you ride in. What's this? A racial city? In outland? Yes. This is Shattrath - to origonal hometown of the Draenei, before they were chased out by Belfs and the Burning Legion and crashed on Azeroth (that had to be such a kick in the teeth). And what's this? The Archmage Khadgar! From WC2! He's talking to... a Naaru. There's several of them about. There's also two factions here which are at odds with eachother - you can't get rep with both. One is friendly to horde, the other to alliance. But most significantly there's a bank here. However, there is also much lore here. Talk to Grumpy Old Khadgar, he'll send you on a tour of the place. Oh, and take a look at the Naaru vendor. If you do 60+ instances on the HARD setting, you get tokens as rewards. Bring the tokens to him, and you get PH4T EPIX. For Example: frostmage offhand with +10 spell penetration (aka 1% to hit with spells) and +47 to frost spells. Motivated to do 5 mans now? Hehe, now think of the things that drop in those instances.
Anyway, that's as far as I got last night with all the bug reporting I did on the way. Place is still really buggy. Will write more later.