Alright, seeing as I've played the full version let me start to produce a wall. Everything is my opinion.
Music. Great, and I never noticed the pop until very recently. Syou's theme is a very nice one.
S6's is designed with the atmosphere in mind, so I won't say much about it. Byakuren's is alright.
The stages were very interesting. Unfortunately, for high-level play, I found only SanaeB useful enough to survive the multitudes of fairies and mass UFO chaining*. Any other shot type (except MarisaB, which does have its uses) suffers horribly at high-level play.
*
I'd honestly like to see somebody do S6 Lunatic without using SanaeB and still be able to chain enough UFOs together without bombing)
Spell Cards were interesting. Some were plain stupid in concept, leading to absurd walling / clipdeath. Nazrin (S5) Mid-Boss' and Byakuren's first come to mind for Lunatic. Even on Hard occasionally.
Still working out the details of the Final Spell Card. And the Shinki-like Spell Card gets +points for nostalgia.
Some of the non-spells / attack phases (AP) were incredibly difficult. Murasa's last is a notable one. Syou's on Lunatic appear to move too fast for me to parse quickly enough.
I also got excited at the "midbosses" for S4 and 6, but... they weren't the same ;_;
At least they gave out some nice things like they did before.
Shot types (and bombs). I'll cover high-level play.
- ReimuA is the baseline.
- ReimuB gets walled too easily, and lacks actual firepower. Bomb is a fair bit powerful, but it really can't be used for UFO chaining too well, since the orbs will attack the UFO.
- MarisaA lasers only seem to be useful for S1 SC3. Spark can't be used for UFO chaining unless you know when and where to bomb. Even then, there are limitations.
- MarisaB has some uses with reverse-shots. I really have no queries about this. Also, short bomb isn't that bad. Maybe I should use this type as my secondary.
- SanaeA is redundant because of the snakes not dealing enough. Bomb is nice though.
- SanaeB trivializes the stages, and is almost as good as ReimuA in terms of long-distance damage against bosses. Shotgunning tips this right over. Delay bomb can be used to the (users) advantage in UFO chaining as well.
Overall Difficulty: Harder than SA, but it gives you a crapton of resources to work with.