Does complex, jargon-heavy writing make you seem intelligent? Apparently not. Before rushing to attack Derrida, note that the study's only real result is that fluency is the key. Increased complexity may not necessarily come at the cost of fluency. Long words are only problematic if used inappropriately.
Unfortunately, the chosen samples weren't much good. The complicated samples read as though a thesaurus had been used to inappropriately substitute words. (Which, for the experiment, it had.) The simplified samples read better, but with significant loss of nuance; even if undergraduates didn't notice, a domain expert would have.
By far the most interesting point came from the fifth experiment. Copies of the same document were divided amongst two groups, but the copies given to the second group were printed badly, making the text (optically) difficult to read. The low-toner group rated the intelligence of the author higher.
[W]hen an obvious source for the lack of fluency is present, people discount that lack of fluency when making their judgement. They do so to such an extent that they end up biasing their judgement in the opposite direction!