A complex sentence is illustrated as the sentences comprising of a dependent clause beginning with subordinate conjunction like before, although, while, before, etc. and an independent clause. Both the clauses, the principal clause and the subordinate clause together propose a complete and comprehensive thought that serves to accomplish the depth of the writing.
As per the question, the given sentence exemplify a complex sentence as it consists of a subordinate or dependent clause 'While Japan has an excellent network of traditional road, rail, air, and sea travel' beginning with the subordinating conjunction 'while' and an independent or principal clause 'the country also boasts the exceptionally fast and safe Shinkansen system of bullet trains'. Thus, it could clearly be justified as a 'complex sentence'.
