I thought Willie showed improvement over the Summer as well as Iguodala, Williams and Young.
As I see it, the team has now moved past the Pistons and the Cavaliers with the addition of Brand, and the continued development of the Sixers' youthful core. Yet to be proven, but they are better on paper.
The addition of another Center, in Mareese Speights addresses the Sixers biggest weakness. Dalembert is as average a Center as you can get, and usually not good enough to get the team to the finals. Speights already has better inside moves. As a rookie, it's going to take him time to learn how to play the right way, and not make mistakes- which he has done in every game he's played in. But if the Sixers can get him developed fast enough to replace Sam when the game is on the line, they should be able to challenge Boston.
I project Williams, Young, Iguodala and Speights as future all stars and all capable of putting up 20 points or better. With Brand and Miller than means they can have 3 scorers on the floor at all times, even when the 2nd team is in. And, whether you appreciate Willie Green or not, he's also capable of putting up 20, particularly against 2nd team 2 guards.
The team was already a very good rebounding team last season, and they should only get better. Their outside shooting has improved as well, you can see it in the confidence with which the Sixers take those outside shoots, as though they know it's going in when they shoot it's going in. Perimeter defense should also improve with Iguodala and Young guarding the wing spots. Andre Miller is not a great defender, but most teams don't have point guards who are great scorers. Assuming they can force turnovers as they did last season, only the best teams will be good enough to force them into a half-court game. And with Brand as a low post scorer, and the improved outside shooting that isn't a such a great formula to beat the Sixers, either.
They may still be a year or two away, as the young players continue to improve their skills. But I think the talent is there now to compete for a title. It's up to Cheeks to figure out the best way to use the players to get the most wins out of them.