Demon the Descent is shaping up to be a really great game! What it means to be a demon, what kind of things demons get up to and what they can do are all very well fleshed out, even though this is only a quickstart guide.
It does have some minor issues though- people hoping to play as the pop culture notion of a "demon" might be disappointed- players do take on the role of fallen "angels", and can look very much like the common image of a demon (though they don't have to), but were once "angels" of the monstrous, mechanical God Machine rather than any kind of Judeo-Christian God (So you're more like Agent Smith from The Matrix than Lucifer from the Bible), and the entire game is filled with references to mechanical devices and computer programming as a result- I personally love this theme, but it definitely isn't what a newcomer would expect.
The only mechanic that I don't like personally is the fact that demons have a sixth sense for "linchpins", the weak points in the God Machine's plans. This seems counter-intuitive, since it robs the great and terrible God Machine of its mystique- how can its plans be cryptic, insidious and unknowable if the weak point is always obvious?
Another issue I have with this quickstart guide is the fact that the story is over-simplistic and gives you some really nice lore about demonic energy, but no way to explain it in the game, short of having the big bad come out and explain it at the end, like some kind of moustache-twirling kid's villain- but even that seems to be ruled out, since he's supposed to be the quiet type. However, a simple story is good for an introduction.
But hey, there's a reason that I gave this thing a five-star rating! It's artwork wonderfully conveys the sense of dark, powerful, mechanical, reality-warping forces at work, the God Machine is given a great description and I love the setting- White Wolf have really taken this project in their own direction and made it something special and unique, rather than doing the obvious thing- like I said, newcomers won't expect this, but maybe they'll be pleasantly surprised?
The powers are good too- the sample demons each possess a load of impressive, clearly described abilities, all with strong ties to the demonic-magic-crossed-with-the-matrix setting.
And the morality system is improved immensely from other White Wolf lines by not existing. Usually, White Wolf games are weighed down by a cumbersome morality system which dictates exactly what is right or wrong and tells you that really evil characters must always be insane to the point of being unplayable and then goes on to stipulate fixed game mechanics for that insanity, rather than leaving it up to role-play. Thankfully, Demons don't need to worry about any of that! Instead, they have a much more thematic problem- they have to disguise themselves with a human identity, which comes complete with a house, a job and other stuff, but if they do enough weird, inhuman stuff, then that "cover" breaks down, becoming more and more like a bad computer simulation than a real identity- this degradation can also come with "glitches" that interfere with a demon's ability to blend in (like changing their hair colour or limiting the kinds of food that they can eat). I find this kind of theme-reinforcing mechanic much more appealing than strictly limiting the player's behaviour with "morality". On top of this, the Virtue and Vice mechanic has been altered slightly, making it more appropriate for strange, inhuman creatures.
Another thing that I love is the number of factions and demon types that are available- they're pretty nice individually, and together they provide plenty of nice, open-ended directions to take your characters in, so that they can have unique goals and methods, rather than being cookie-cutter characters.
All in all, this game provides plenty of cool options to let you play as something vaguely like a cross between Agent Smith and the devil, and has the mechanics and story in place to make it a truly unique experience- as long as you can let go of your preconceptions and embrace the weird, wonderful, flavourful setting, you're sure to enjoy yourself!