Well, I think I "got" it almost immediately.
It's basically a melee class using Intelligence in place of Strength for attack rolls and damage rolls. The control effect comes from at-will powers that trigger every time the character hits with a melee attack. These automatically affect an enemy - no need for an attack roll, and not necessary the one they hit - and deal a small amount (Dexterity modifier) of damage plus some small effect (target grants combat advantage, target takes a -2 penalty to attack rolls, target is slowed, target takes damage if it moves, target is prone, target is slid 3 squares). It can thus function as a once per hit minion killer, or the bladesinger could be attacking one enemy in melee and messing with another within 10 squares. (The bladesinger also doesn't provoke AOs for using ranged powers when fighting with a one-handed weapon and nothing in the other hand.)
The encounter power grants it a bonues to attack rolls and defenses, and a larger bonus to damage rolls. Based on the preview, it gets other encounter powers as it levels up.
It also gets three cantrips (chosen from ghost sound, light, mage hand, prestidigitation, and suggestion) and the magic missile spell.
The only questionable design decision that I can see is that it uses wizard encounter spells as its dailies. I'm guessing that the somewhat more powerful and flexible at-will abilities are supposed to compensate for that.
Well, it uses Wizard dailies since it is a subclass of Wizard. Wizard, Bladesinger.