I started my session the same way as if I'd just installed it at home, which is by dipping into CAS and seeing what's new.
First thing you see there is the new button allowing you to select which type of Supernatural you want – or a normal human sim! Genies were there, but greyed out, as Showtime wasn't installed, but you could pick Vampires, Werewolves, Witches, Ghosts and Fairies.
The other new thing on the overview screen is the first new skintones EA have introduced to The Sims 3, 6 of them, to be precise! The promised Rainbow skin tone is there – not one, but two of them in fact! There's a pastel version and a brights one. There's also a golden tone, a turquiosey-one, a purple one and finally a black and white one. As with the existing blue and green tones, the palest end of the spectums are light enough to be used for normal sims. Well, normal-ish! 
There's no specific options available that I spotted for Vamps or Witches in CAS.
Ghosts, you can pick your own death type. There are 12 available, including the new Death by Jelly Bean… which is a gorgeous bluey-purple ghost!
Fairies can customise their wings – 6 different styles are available and are all CASable.
Werewolves can have both human and wolf faces designed. The wolf chin seems to be very prominent, so I don't know that it would be possible to either make very human looking weres, or other species such as weretigers.
There's also new make up available – eyeshadow, blush and lipstick designed to give your sim that "just out the grave" look, and a new vein-y face paint for the wolves.
New traits I spotted – Brooding, Gatherer, Supernatural Fan and Skeptic, Night Owl and Proper. Gatherer and the two Supernatural ones have been discussed elsewhere; Brooding gave my sim the option to Contemplate the Hollowness of Life or the Meaning of Meaning, while Proper seems to be the old fashioned type manners – great for Vamps! Didn't see the effect of Night Owl, but would imagine it lets them cope better staying up at night, and is probably connected tot he "Stay up past bedtime" wish my sim got. Bedtime for the purpose of this being 11pm.
I spotted 4 new LTW. Celeb Psychic, Mystic Healer, Turn the Town and Zombie Master. I chose Mystic healer, which wanted my sim to cure 12 different sims using either the Sunlight Charm or the Potent Cure Elixir.
New clothes for all sims, not just the supernaturals, include torn clothing for zombies and werewolfs and some vaguely Victoriana style outfits that should inspire the history aficionados without looking out of place.
Fairy sim created, I headed for a look at Moonlight Falls. First impressions are it's large and very open and spreadout. The river and waterfall kind of remind me of TS1 a bit. The Gypsy wagon and the Arboretum (I think that's the right spelling!) are both rabbit holes, which function like the Mausoleum in that you get options popping up to control the adventure. There's two new lot type – Supernatural Hang Out (who'll be the first to build Shreveport's Hair of the Dog bar?) and an Elixir Consignment store when you can buy and sell ingredients and finished elixirs.
Next stop, place my sim in a house, and have har Fairy godmother motherlode her some space simoleons,
On her lot, and in buydebug, there's some huge air-con units. Hunting around, I found loads of stuff.
I added the train set to her lot, since I wanted my Fairy to test it out, a LLAMA machine – which looks great TARDIS Blue – the alchemy station, planters, a Fairy bungalow and Bonehilda. I also found the broomstick stand, so added one of those and a broomstick, and also saw baby broomsticks! Child sized broomsticks with stabilisers for kids! Anyone who's read Harry Potter will recognise the idea, and I was over the moon to see them!
Fairy shrink down for the train set and the bungalow is cool – in fact using the Fairy bungalow, you could have an almost totally outside lot for them.
Bonehilda is back,and her old, bony self. She's non controllable, and your sim can chat to her to increase their social bar, but she doesn't appear in the friends list.
The LLAMA machine allows almost instant travel between machines, Works like the subway, or the digger holes, but a lot faster. Just watch for overuse. One sim with the Supernatural Skeptic trait used it twice in close succession, and ended up with the Tragic Clown moodlet from using it! Sww has given details elsewhere, so that's at least two ways now to get the tragic clown around!
The pink bar you may have spotted about the Fairy in the chat shows their current level of magical power – energy, not skill. It appears for witches as well as Fairies.
Any sim can ride a broomstick, but there's a lot more to becoming a witch that just buying a wand! I didn't play that long with a witch, but I did discover that some sims can be immune to certain spells.
Jelly beans grow on a bush, and you can buy both that and the new planters under decor/plants in buy mode. I didn't discover how they cause death, but the girl sitting next to me found that with each bean her sim ate, she was getting progressively worse moodlets! Make of that what you will!
New lifetime reward include sunscreen and immortality for Vampires, an upgrades broomstick, called a flying vacuum, a Philosopher's stone for Alchemy and for Fairies, the chance to be King or Queen of the Faeries, which allows the to Summon The Troop.
Returning and related sims that I spotted were Titania and Oberon Summerdream. I also spotted Frida Goth's ghost, although I'm not sure if she was playable or a floater, three Crumplebottom sisters and a Caliente. Also tied into Magic and Shakespeare was a MacDuff. Also, the name around town, similar to the Landgraabs in previous games, is Aleister Krummly. Hmmm, wonder what sort of magic he's into!
New book spotted – Plan 8 from Lunar Lakes. New quick mean – Brain Freeze a la mode. New moodlet – starved of moonlight.
Speaking of moonlight, you can either fix the lunar cycle to a particular phase, or you can have it on a cycle of anything between 2-10 days.
In your friends list, different supes will glow different colours, just like Vampires do at the moment.
Werewolves have the option to howl at the moon, and to sniff people inappropriately.
Promise to protect is a new romantic interaction, as is "Confess to watching while you sleep". So combine with the apparent sparkly effect of the sunscreen, and you too can have your own creepy stalker vampire. Sadly, I didn't find the stakes.
I played for two hours and could easily have played another 2, there's so much to explore. This looks to be a fantastic pack, and I don't think I've been so exited about a Sims release since TS3 itself!