The issue that I see with the Shade is:
(a) The free stealth skill (which is better than a background, since it doesn't count as your normal trained options) is wasted on the Rogue and Assassin.
But
(b) Being hidden is best used by those two classes. Only the Rogue is dependent on combat advantage for it's bonus damage, and the executioner assassin has a few powers that require he be hidden.
For characters outside those classes, combat advantage is nice, but not something that is necessarilly worth say giving up a standard action to do. The -5 to being hit is a powerful motivation if you can pull it off, but if you are not a rogue or assassin, it will often mean using up a standard action to do so ... thus not attacking an opponent to make it harder to hit you.
Of course, it's possible there are other things in the book that can work well with the shade. The old warlock could forgo their INT to pump up DEX and combine shadow walk with stealth, while the fey pact hexblade does use a light blade and DEX as a secondary stat, so light blade expertise would at least give a little bit of a bonus. I do remember someone mentioning that the Blackguard that was previewed did have some kind of combat advantage dependent striker damage, so they may end up being a good person to have as a shade. And, at the very least, the druid and ranger essential builds can take their stealth for free to use with their knack/stances and be able to grab an extra skill (like athletics which, while not fitting their primary stats, again ties into a knack).
It will be interesting to see the rest of it. Just seems a shame that shades are "too stealthy" to be Rogues or Assassins basically.
EDIT:
The only riot I've been involved with (and mostly at the table complaining instead of on the boards) was the last minute "by the way" where the Assassin was not just going into the book, but the at the time final version was labelled a playtest article for the book (or three playtest articles) so it wouldn't make it into the CB until HOS drops and gets it's content put in. Since our DM was allowing the rogue to become a thief next level, I had been looking forward to becoming an Executioner, but that all went out the window.