Permit me to enter this thread with a suggestion.  I don't know whether
Mahler should be viewed as "overrated" or not, but I would designate him
(perhaps in a dead heat with Wagner) as "most overstated".  By this, I
refer the simple ratio of what is achieved to what is employed.  Consider
the following comparison of two works, and the means they employ.

Mahler's Symphony #2:  about 80 minutes, requring a large symphony
orchestra, organ, chorus, soloists, bells, whistles, and if Mahler were
composing today he would no doubt call in Stephen Spielberg for special
effects.

Bach's chaconne from the partita #2 in D minor:  14 minutes, one violin.

Jon Gallant