This is a work so hugely influential to IF development that anyone interested in the history of the form should try it: it experiments with non-linear presentation of time, menu-based conversation, and constrained game-play to support a specific plot. A number of its features look perfectly ordinary now, but were ground-breaking at the time. Photopia's particular form of menu conversation, for instance, was spun off into a library used in a number of other works.
How well does it work, beyond that? Opinions vary. Some people consider it the most moving piece of IF they've ever tried. I personally found it wavered between effective and manipulative, with the main character too saintly to be true. While it was worth playing, it is by no means my favorite piece of character-oriented IF story-telling.
This is a piece I sketched up one evening apropos of a rec.arts.int-fiction discussion on simulation and puzzles. As a game, it doesn't have much to recommend it, unless you really enjoy coming up with diverse ways to destroy various materials.
This is a pretty entertaining send-up of the later portions of Spider and Web. It is spoilery and incomprehensible if you haven't played the original game; worth the five minutes of amusement if you have.