The 1981 compilation Assemblage gives a skewed, incomplete picture of Japan's early career; this is not necessarily a bad thing, as Japan's early career frankly wasn't very good, and it certainly had little to do with the mature, studied art-pop of their later albums.
For example, the glammy disco thump of the opening "Adolescent Sex" has more to do with the Sweet than Brian Eno, and the version of Smokey Robinson & the Miracles' "I Second That Emotion" taken from a 1980 single sounds more like a failed attempt at chart success than an artistic experiment.
Furthermore, David Sylvian's voice is completely different on the early tracks here, a nasal whine that's difficult to listen to for more than a few minutes at a time.
That said, there are a few not-bad tracks here.
"Communist China" is intriguing post-punk that hints at the loud-soft dynamic of Gentlemen Take Polaroids, and "Rhodesia," a not entirely successful reggae experiment, at least introduces the use of world music forms, atmospheric production, and smoother, more controlled singing that would characterize their later career.
That later career starts on side two, where, after the electro-disco sidetrack of the Giorgio Moroder collaboration "Life in Tokyo," Japan's sudden left turn into artsy soft rock begins with the original "European Son" and an imaginative reworking of the Velvet Underground's "All Tomorrow's Parties." Assemblage isn't entirely essential, but with its singles and previously unreleased tracks, it's a better starting point than either of Japan's first two albums.