I think at first glance, my favourite card is easily [card]Abyssal Persecutor[/card].
4 to cast 6/6 flying trample - with a drawback black can easily deal with. I'm not so sure about its viability in tournaments, but it's certainly a chase mythic (unfortunately).
First, let's take a short glance at white. White hasn't really gotten much of a boost, and the only thing that interests me now (because it's Extended season, if I'm not mistaken) is a timeshifted version of [card]Kird Ape[/card] too. It's called [card]Loam Lion[/card].
Other notable white cards are [card]Rest for the Weary[/card] and [card]Stoneforge Mystic[/card].
They printed a counterspell for instants - which isn't too bad, considering the number of good instants in the current metagame ([card]Lightning Bolt[/card] and [card]Path to Exile[/card] come to mind.)
I don't know what to think about [card]Jace, the Mind Sculptor[/card]. It's still an awesome card with plenty of power, but as I've learned with planeswalkers - the one time a turn thing can really bum you out sometimes.
Other notable blue cards are [card]Mysteries of the Deep[/card]. [card]Selective Memory[/card], [card]Thada Adel, Acquisitor[/card] and perhaps, [card]Treasure Hunt[/card].
Besides [card]Abyssal Persecutor[/card], I think [card]Death's Shadow[/card] and the reprinting of [card]Smother[/card] is interesting.
As for red, [card]Bazaar Trader[/card] is interesting, being a [card]Donate[/card] that ignores enchantments (and planeswalkers). Although, I think my favourite red card is:
In green, there's [card]Canopy Cover[/card], although I'd imagine the all green version of [card]Woolly Thoctar[/card] (I know it's not exactly the same - but the idea is the same.) is the most interesting green card to me.
[card]Everflowing Chalice[/card] is useful in many of my decks, although in many cases I would play [card]Gilded Lotus[/card] instead. [card]Basilisk Collar[/card] is also interesting, and although I'm not sure how good it is, I'd sure like 4 copies of it.
Among the five new dual colored manlands, [card]Celestial Colonnade[/card], [card]Creeping Tar Pit[/card], [card]Lavaclaw Reaches[/card], [card]Raging Ravine[/card] and [card]Stirring Wildwood[/card], I like [card]Celestial Colonnade[/card] the best.
And that concludes my quick look at Worldwake. I'll post more once I've actually played with the cards. No time to go to the prereleases yet again, sadly.