OK, to get back on track: I really dig the Valis series. Valis III is my favorite, by far. Excellent game. It felt wonderful to beat it, since you had to develop strategies for passing some particularly tricky sections of the game. Stage design, during these segments, was pretty kool! Otherwise, most Valis games are quite linear with basic stage design. Valis IV is quite enjoyable, but I have to say, Valis III is still my fave.
Valis I is interesting, but not nearly as atmospheric as Valis II. If Valis II had more inspired stage design (and I think there should have been more stages, to elevate it to an "adventure" instead of merely a "romp") and was more challenging, then it would have been incredible. Amazingly, the story in Valis 2 is more comprehensible than that of Valis III. How is this even possible?
I haven't really spent as much time with Valis I PCE as the others, so I'll reserve judgment on it.