Wow, surprised the Wandering Swordmage is doing as well as he is. It's my favorite PP of my favorite class, but I like it more for fluff reasons than mechanical reasons. Mechanically, I think it's kind of a stinker. As people have already said, you have to plan from level 1 if you want to play as one. Aegis Insight has the potential to be powerful, but I have a hard time justifying a Wisdom higher than 15 at level 1. That comes out to a +3 modifier at level 11, boosting your Aegis burst from 2 to 5. Significant, but game-changing? Not sure; haven't see it in play. "Learn From Experience" is, in my opinion, downright weak for a 16th level passive benefit, requiring you to be hit by a crit, survive, and be close enough to counter-attack before it even comes into play. "Arcane Tanglestep," the 12th level utility, sounds sweet, but I doubt it'll really beat an 11th level Swordmage's normal Aegis-violation immediate interrupt. "Heritage of Blades," however, is sweet. Minor action attacks are delicious, and the flavor of the power just meshes perfectly with what a Swordmage should be, I think.
What I like best about the PP, though, is that it doesn't come with a lot of baggage. For some reason, the creators decided to present Swordmagic as this ancient, esoteric form of magic brought either from the Feywild by eladrin or the genasi from the Elemental Chaos. And that's cool and all, but it's just too similar to wizardry for me. I prefer to think of my Swordmages as self-taught virtuosos, boldly pioneering some new form of magic. Or as quasi-insane magical improvisers, constantly experimenting and teleporting around almost on accident. Or (my personal favorite background) mages whose academy was burned to the ground while they were still learning the basics, so they've been forced to combine their natural magical ability with swordplay to survive.
Point is, Wandering Swordmage just seems appropriate, because let's face it, that's what most adventurers are going to be. They're not going to have time to study the ancient styles of Shyr or what-have-you. They're just going to pick up whatever dirty, slapdash tricks they can.