Well, there's a lot of fancy talk there about kicking system mastery in the teeth and making any combination work equally well, but it doesn't look likely to work out that way.
Take the Student of the Sword feat, for instance. If there are a limited number of attack bonus boosting feats--even if many of them are better than Student of the Sword, it's still an obvious power choice for a warrior type. And no matter how often the designers pretend that healing word 1/day is as good as +1 to hit, there are a lot of characters for whom the +1 to hit is going to be a lot better. (Marking, etc, we'll wait and see on, but +1 to hit is an obvious and obviously useful benefit).
Conversely, the power trading feats have a long road to hoe in order to avoid being traps for the unwary. If they work as described in the article, a character who takes a power trading feat gives up a feat and a power to get a power that wouldn't normally be available to him. Now, if everything works as advertised and all powers are equal (no really, I'm trying to be serious here, WotC designers said it, it must be so), then the character who sticks with his ordinary class powers gets a feat and a power but the character who wants to trade simply ends up short a feat in comparison. What is most likely to happen is that there will be a couple powers that are significantly better than other powers (at least for certain types of characters) and that characters who use the power trading feats to gain those powers will be somewhat stronger than they would without the power trading feat. At the same time, players who make more suspect choices will end up with a power that doesn't really help them do anything that needs doing and will have wasted a feat for the privilige of gimping their character like that.
We'll have to wait and see what all comes out of it, but it doesn't look particularly promising to me as a multiclassing system.
In the meantime, I'll note that saying at the same time that the new system does fighter/mages perfectly fine and that it only allows dabbling is complete and utter doublespeak.