During his own time, Gustav Mahler was considered as one of the major conductors of Europe, but nowadays he is considered to a major composer who bridged the Late Romantic period to the modern age.
Few composers are so connected with the symphonic repertory as Gustav Mahler. Composing symphonies was his "core business": in every aspect he developed the symphony towards, and sometimes even over, its absolute limits. Almost all of Mahler's symphonies are lenghty, demand a large orchestra and are particularly great in their expressive qualities. With rustic and mythical atmospheres (the start of the First Symphony), daunting chaos (the end of his Sixth), grand visions (end of his Second), cheerful melodies (opening Fourth), romantic melancholy (the famous adagio of his Fifth), evocations of nature (his Third), megalomanic eruptions in the orchestra (his Eighth), and the clamant atonality of his unfinished Tenth, Mahler's musical palette seemed inexhaustible.
His symphonies are captivating, but some could find it a bit 'over the top' at times. For those, his orchestral songs could undoubtedly show there is an incredibly subtle and refined side to his compositional style as well.
In the Netherlands, Mahler is particularly popular due to its close bond with the Royal Concertgebouw Orchestra, which was already established during his lifetime!