As one who entered the Touhou fandom right around the time of UFO's release, this is really my first time anticipating a new game.
Firstly, my conclusion: it sucks.
This makes me extremely uncomfortable, given that I can't tell whether it actually genuinely truly sucks, or whether I'm experiencing a kneejerk "It's different, therefore horrible" reaction. However, after mulling it over a while, I've been able to articulate several clear points that capture my displeasure, and in so doing, appreciate the elements that are in fact quite promising.
First point: Spirits. Where do they spawn? Why, above the PoC, naturally. Do they move? Hell no. So, go up and get 'em! *enemy spawns on top of me* WtH, ZUN? That's just mean! They have got to be easier to collect. Don't care if they drift slowly downscreen, or have something similar to SA's graze meter or whatever, but dammit, do something with them! At least UFOs came down to you, instead of making you chase them. (o wait :V)
Second point: Yuyuko. Why, ZUN, why do you do this? Touhou is Touhou because it has a zillion and one new characters in every game! Recycling is something you don't do! That said, I did just about have an orgasm when I tried hard and Yuyu pulled her fan out, so meh. Kogasa doesn't seem to bother me as much, especially when you consider my natural prejudice against stage 2 bosses; that may just because I was already raged out by the time I reached her, though.
Third point: The lifebarscircles. They were okay in GFW 'cuz once you launched your freeze, you had time to make a sandwich, read a newspaper, check the boss's life, whatever, and then back to dodging. Here? If I have half a second between waves, it's much, much easier to flick my eyes at the top of the screen than it is to locate the boss and track the circle looking for the end of the line. And that's if it isn't being blocked by bullets.
And that's my piece. Now for some more level-headed commentary:
Characters. Kyouko is cute enough to overcome my stage-2 bias, and her gimmick is pretty neat, but I feel like there's a lot of wasted potential in it. Especially her Resonance spellcard. The waves are surprisingly weak, given that most of the bullets get recycled in the next box, and you get a year-long break in between them. Maybe something to work on in Danmakufu, eh?
Yoshika is... forgettable. However, I do like the idea of healing yourself during spellcards; figuring out how to get in close and collect those spirits as she's drawing them in is probably the most fun part of the demo for me. I dearly hope that later bosses in the game have similar spellcards, but if it happens to be Yoshika's gimmick in particular, then, well, good on her.
Shottypes. Homing!Reimu sucks as usual, Marisa and Sanae feel pretty solid. Youmu is the obligatory "awkward focus" type which ZUN seems fond of, but is pretty strong to compen-HOLY SHIT, IT'S MOF MARI-A ALL OVER AGAIN! Overall, a decent selection (if disappointingly small).
Music. I'm no afficianado in this regard, but it seems like it's expanding on the elements of UFO's score that I didn't like. Maybe the instrumentation or something, I don't even know. I'll wait for the remixes before passing judgment.
All in all, it's quite unpolished (Have all his demos been like this?), but it's got some potential. Just as long as he doesn't bring back any more old characters. ('cept maybe Mim-*shot*