By the third installment, the dialogue was fully recorded by singularly appropriate speakers, which greatly increased the enjoyment of the player ("Thanks to LeChuck?'s seminars, motivational speeches, and audio Books-on-Parrot, I've become a vicious corsair! You can too! Ask me how!" - the 'evil pirate Bloodnose')
Unlike their contemporaries from Sierra, LucasArts adventure games refused to allow their protagonist to die, which resulted in some of the more memorable little sequences where Guybrush performs some dangerous or really stupid act. This encourages the player to try out every option, no matter how ridiculous, since it will not result in the game ending or having to reload a saved game.
The puzzles often seem much more difficult than they are, generally because it can be hard to warp your view of the world to adjust to a place where sword fights are actually fought with insults, where the local cannibals are trying (for health reasons) to give up red meat, and where the grog which is being happily drunk in the SCUMM bar dissolves away the mugs that hold it. And this is just from the first installment.
Trivia fans will want to know that SCUMM stood for "Script Creation Utility for Maniac Mansion". This is the computer language used to write the adventure.