The biggest differences so far this year:
-Koeman has not hesitated to make changes early when things are not working. Down a goal away to West Brom, with the team lethargic, he pulled McCarthy and inserted Lukaku at about the 30' mark IIRC. Even though Lukaku was not yet match-fit, his presence energized the attack and Everton went on to win 2-1. Similarly yesterday: after a scoreless first half where the team had played listlessly, Koeman benched the frustratingly inconsistent Barkley (rumor has it he was in a funk over being passed over for England, but given the hole of suck that is England, maybe they did him a favor) and put in Deulofeu. With Deulofeu and Bolasie providing lots of pace and wide threats, and Gueye and Barry staying poised and controlled in midfield, the attack shifted into high gear, and we saw what Lukaku can do with when the midfield sets him up well.
Koeman maanges like Playoff Tito. It's fun to watch.
-The offseason looks like it was fruitful. Gone is Stones, but he didn't want to be there, and they got tons of cash for him. Keeping Lukaku was a coup, and although he is always a threat to leave, he seems to have a soft spot for Everton after he came into his own there while on loan from Chelsea. Losing out on Sissoko, even though fans were pissed off on the Merseyside blogs, was a blessing - he was way overpriced, and based on what we have seen so far, the Everton midfield is potent without him. Gueye has a lot to do with that: this guy is a gem, and may be the steal of the transfer window. As per ninja, he can do it all and carries himself like a 15-year veteran. Another great addition has been Stecklenburg; although Robles was good enough to run Timmeh! out of town last year (I had a sadz; I am a fanboy), he was not/is not the answer, and Stecklenburg has excelled both as a shot-stopper and as the general of the defense.
-They keep their shape. It's such a basic thing, but for the second half of last year, everyone more or less wandered around aimlessly, and the attack was predictable and ineffective: passes back and forth around the perimeter between the midfielders, Lukaku with his back to the goal and no one feeding him, and finally a shot from Mirallas or Barkley from 25 yards out that went into the tenth row. It's nice to see actual football this year.
We'll see what happens when they start playing heavyweights, but so far, they seem to have the tools to compete.