One of the weird things about Oriental Adventures is that a lot of its supplements feature random Chinese characters as part of the art - that is not so weird by itself, but almost all of the (random) characters say "fu" (foo). So, it basically says, "fu fu fu fu fu fu fu fu fu fu," in various ways, with the various meanings that "fu" can have (float, rot, abundant, etc.), depending on which character it is. But why did they choose "fu?"
Another characteristic of Oriental Adventures was the addition of a new ability score, i.e. Comeliness. Originally, the Charisma score basically handled both personal charisma and physical appearance, but this new mechanic basically split these two apart. Further complicating things, high Charisma affected Comeliness positively, while low Charisma affected Comeliness negatively, so that one could have extremely high (or low) Comeliness scores if one was very lucky (or unlucky).
Separating Charisma into Charisma and Comeliness enabled players to be able to have ugly yet nice, or beautiful yet prissy PCs, where in the past these two features were averaged together in a single ability score (Charisma). In 2nd Edition AD&D later on, Charisma seemed to be relegated to personality only, with looks being decided by the player on his or her own; however, Forgotten Realms campaigns continued to use Charisma in its old double meaning.
Regarding character classes, Oriental Adventures offered a bunch of new classes, as well as a few old ones. I enjoyed the kensai (which should be "kensei") and sohei most; the bushi was redundant (a fighter who could pickpocket), the samurai was too powerful (why should a samurai be any better than a bushi?), the shukenja (which should be "shugenja") was too weak, and the yakuza was kind of silly. The kensai was pretty cool - a warrior who put his whole life into the perfection of a single weapon; the sohei was also interesting, as a temple warrior with some priestly powers. The wu-jen was a sort of strong wizard-type, as he had 1d4+1 hp/level (as opposed to just 1d4); with martial arts, you could have a fairly strong wu-jen with naturally high AC, fair hp, and good melee damage as well. (I played a crane hengeyokai wu-jen online for a while at DND Online Games, until the (somewhat flaky) DM quit! Ah well, it was fun while it lasted!)
The monk, mostly the same as its Player's Handbook incarnation was mostly still the Kwai Chiang Kain-esque barehand martial arts master - which is, of course, strange, since Chinese martial monks were known for using various weapons, including iron-shod staves and sickle-bladed spades, but also scimitars, swords, double hook swords, and so on. Of course, they were still quite powerful without any weapons, but the addition of weapons obviously made them even more formidable in battle. (Shaolin monks, for example, were famous for their staff techniques, while Wudang ascetics were known for their sword skills.) The monk class, while potentially quite deadly at higher levels, was exceedingly weak at lower levels, and so it probably would have been better to at least give them access to some of the more powerful weapons.