Meh, underwhelming set at 1st glance. The obvious standout best cards are white (Gisela and Thalia seem the most powerfull cards, the 3 mana escalate removal seems strong also and the Thalia's Lancers+Bruna combo seems sweet). Black got some nice new toys also. Green didn't seem to get much and blue and red got in general pretty screwd again (there is a lack of pushed for standard cards).
There seems to be a lot of support for delirium, although I'm a bit sceptical of how good it still is since the cards are mostly very aggressive oriented and losing tempo to achieve the delirium seems a nonbo with the strategy itself.
I don't think neither vampires or zombies will make a splash. The new cards seem to be very powerful when the synergies are going but very underwhelming when they don't happen and that was the problem of these decks. I was expecting them to reprint stuff like Gravecrawler, Geralf's messenger or Falkenrath aristrocrats or print stuff with similar power level but I guess Wizards doesn't like competitive tribal.
The emerge Eldrazi (deep fiend, craterhoof 2 and the double discard one) seem very powerfull and the haste land also seems quite good(especially good vs planeswalkers). Not sure if Emrakul is better than Ulamog in midrange decks, it will need testing.
Overall I except both standard and duels metas to be mostly unchanged, with every deck getting minor upgrades and a GW based midrange deck still dominating.
I think UW flyers/spirits, GW humans/tokens and a bant combo will go well. Don't think vampires and zombies are strong enough.
Not sure about control though, I'm sure the good control players will figure it out.
Well as one of the de-facto humans players, the card I am most excited about is:
And if I'm right, it will be sufficient, all on it's own, to make Boros Humans the real deal. You'll have access to red direct damage and removal, as well as one of - if not - the best 2/3 drop package for an aggressive shell. That card alongside Hanweir Captain, and Thalia's Lt is going to be very strong, possibly strong enough to justify the whole deck, which wasn't particularly bad before the expansion.
Don't forget that
Abbot of Keral Keep is still a card, even though it's been unplayable this season.
Also, Green is getting some fantastic 1 drops.
and
Both look very playable to me.
Obviously, we have no idea what we'll be getting, but still... Don't underestimate this set too much.