I want to say I love L'avventura... it's unique and considering it arrived in 1960, way ahead of its time in terms of the method of plot delivery. This film basically has a surprise beginning, as opposed to a surprise ending. My beef is that it was a smidge too long (2:20).
At the beginning, Anna is the centerpiece. She and some friends are on a remote island when she disappears without a trace. Boyfriend Sandro and pal Claudia pursue the few leads that surface without success. Then at some point (I'm not exactly sure when), they don't really care about finding Anna anymore. And neither does the viewer. It becomes clear that the film's focus is Claudia, not Anna -- and not Claudia's physical adventure tracking Anna, but her emotional adventure with and without Sandro. Sandro is a tool. Claudia should realize it, but doesn't until the end.
The disc looks great. It's Criterion, and you know those guys can restore an old film like nobody's business. Rent it.