Valis' opening episode was actually the last to be brought to the PC Engine and is by far the most forgettable of the bunch. A fairly straightforward hack-and-dash title, it's short, easy, and basically just okay in every respect. Among the PCE Valis games, it's most comparable to II in that it places much more emphasis on combat than on platforming, and its level design isn't as advanced as III's or IV's. Its decidedly unmemorable soundtrack doesn't even come close to II's; but its gameplay is a little more enjoyable, as it isn't as sloppy. Main-character Yuko "runs" quite slowly, but this becomes less of a pain as you get used to it.
I dig the visual style in this game; everything seems kind of small, but the animation is smooth, and the colors are appealing.
I've read some negative commentary on the cinemas, but aside from the "small windows" issue and Yuko's face looking a little weird here and there, they are actually pretty nice and feature some fairly dramatic moments.
The boss designs are interesting, and while the beasts here generally aren't as large as the lumbering heavyweights in II, they're definitely better fighters.