Alright, I checked out the voice actors, and here are my opinions so far.
Sakuya's fits, I guess. I've always thought she should have a somewhat more mature voice, though; this one sounds more fitting for Reimu.
Remilia's fits perfectly.
Couldn't find a sample for Patchouli.
Oh shit Flandre is perfect.
Couldn't find a sample for Meiling.
Reimu's good, but I feel like she and Sakuya should switch.
No sample for Marisa.
Same with Alice.
Yukari could grow on me. I think she had a good choice.
Yuyuko fits too. I was surprised, honestly.
No Youmu sample.
Same with Ran.
....Chen and Marisa are the same person. I'm kind of worried about this.
...and Komachi and Alice are the same person. See above.
I'll save my reservations until the game actually comes out, but it looks sufficiently promising so far on the VA front.