What a strange little game.
Played one on a whim and finished it in a day. It's not exactly hard but it's fun.

It's a nice little time capsule to see how far touhou has become so I don't know if I can rate it fairly by looking at it from a modern lens. The ideas are all laid out here, like with one of Karumi's attacks being really similar to Nazrin's first spell card, Rare Metal Detector. It's cool!

There's some weird mechanics as it's one of the PC98 games.
Bosses are really short.
There's basically a survival spell at the end of every stage (except 6). Yuuka's master spark is unreactable so you just have to know when she's gonna use it (so it's not so bad).
No visible hitbox. Movement is really sluggish but easy to get used to.

Some backgrounds for stages 3 and 5 make it really hard to see bullets, I think that's from the limited colour palette of the PC98 (is that why Reimu's hair is purple?).

There's a lot of parts, much more than later games (I don't think it's even a thing in the windows games), where enemies just try to run into you to deal contact damage. It's strange to see but it's interesting.

When you use a bomb, it shows a really cute image of the character you're playing. This should come back, ZUN please.

Bad Apple still slaps and it was nice to hear the original.

If you can get an emulator working (I used Neko Project 21) then I would recommend it at least for the history.