Explicit predicate structure of arguments. Which throws natural language notions of case out the window (although prepositions are included as well): it really is a matter of argument #1, argument #2, rather than accusative, dative, etc.
Very explicit, computer-parsable syntax, with spoken brackets for syntactic structures.
Logical, rather than natural language, notions of negation. (Again, more natural representations are included alongside it.)
Berserk allomorphy in compounding, and no distinction between derivational morphology and compounding.
Differentiations in determiners that are also very logicish and independent of definiteness.
No substantial noun/verb distinction (the terms are avoided in Lojban); a noun is just a verb with a determiner, and thus can have tense or mood the same as a verb.
Locative as well as temporal tense and aspect, and explicit Vendlerian categories of aktionsart.