Jumping in a bit late here, but I like the Bladesinger (or Bladeslinger as the pdf file name says) quite a bit. It solves many problems with the typical controller.
The blade singer, for all intents and purposes is a striker. They have a good basic attack, which means they can abuse charging, they have an at-will striker mechanic, adding a well scaling second stat to damage against a target, allowing single target striking, and they have a level 1 encounter power that's basically a striker mechanic for increased accuracy and damage for two rounds. All of this adds up to, striker. In a radiant group or against undead, they become even better by double dipping into radiant vulnerability with Dazzling Sunray.
Looking at their control, they basically can have 3 at-will options from some great choices like prone, -2 attack, slide 3, etc. The main problem of a controller in exerting control, is that the thing you want to control is not always the thing your party is focusing fire on. So, while your allies are daling with front line brutes, as controller, you might feel it's a good idea to slow the skirmisher that's about to charge into your flank, or give the AoE artillery a -2 penalty to hit. This usually takes away from focused fire. But in the Case of the Bladesinger, he can focus most of his fire on the target his allies are beating on, and send an off-shoot attack for control where it's needed. This is almost like the Monk's flexibility with Flurry of Blows.
Using AoE's for minion clearing has a similar problem, you might find a decent grouping to blast, but there is maybe one standard creature and two minions in there. You may have no interest on starting damage on that one standard creature. It is again much better to focus your damage on the priority target for the party, and send a backhand slap to kill a minion elsewhere. This works even better on bigger maps where AoE's fail. It's maybe not quite as good as the Invoker's Hand of Radiance, but that's perfectly fine.
The survival tools are just right for a melee class. I see nothing wrong with any of that. The class will still have a weakness in two defenses (except some of the stranger builds that ignore Int), which I see as a good thing.
And there are plenty of wizard encounter powers I wouldn't mind having as a daily on a Bladesinger. I see these as more part of a tool box to deal with various situations. Some examples would be Icy Rays, Color Spray, Fire Sea Travel, Twist of Space, etc. Being able to boost the accuracy and damage of these daily powers with your encounter power is just gravy.
This is the first class where it seems someone paid attention to make sure a melee class has a decent melee basic and a ranged at-will, without having to resort to an item choice like farbond spellblade or dwarven thrower weapons, or give up one of two at-will slots like many avengers have to do. and Many builds like charisma paladins and the like are just out of luck when it comes to ranged at-will attacks.
I'm not really sure if the class needed a spell book per se, I rarely see wizards making any use of that, but I might just be a corner case. I find it's more complications than it's worth, but whatever, I'm not fretting over it. Overall, I think it's a well thought out class.
Much like this class, I think the controller role needs to be demoted from primary to secondary role. There shouldn't be a class that has controller as a primary role. There is no reason why you couldn't give preserving invokers a once per encounter healing word, and call them leader/controller. You could give swarm or guardian druids a boost to defenses and a marking mechanic, and call them defender/controller. You could give Wrathful Invokers and Predator Druids +secondary stat to damage or some other striker mechanic, and call them striker/controller. I think pure controller is just a hard to grasp role.
