I had assumed that the slayer would be a replacement for the decidedly 'secondary striker role' Greatweapon Fighter build, so the striker role isn't a shock. Apparently, it's an alternative to both the Greatweapon and the Battlerager builds, and can be a pretty good archer into the bargain.
As with the Knight, Melee Training could be used to make it's secondary stat into it's primary, meaning only one stat need be maximized.
It's awefully tough for a striker, having Barbarian level hps and better AC out of the box than most barbarians. A Melee Training (DEX) take on it could have very good AC in hide, too.
The Essentials martial classes are seriously re-imagining the place of the basic attack in the system. I suspect there'll have to be a lot of nerfing and/or re-balancing of feats/powers/etc that relate to basic attacks in the massive October errata.
The Essentials classes are also definitely bluring the line between 'build' and 'class.' Where the Warpriest and Mage are clearly just builds of Cleric and Wizard, the Knight and Thief might as well be different classes from the Fighter and Rogue, and the Slayer being a different role makes it very much distinct from the Fighter, and from the Knight, for that matter.