Modern orchestral libraries are recorded in lush, reverberant halls like Air Lyndhurst or Teldex. They rely on "room tone." Orchestral Essentials, by contrast, sounds like it was recorded in a very well-treated living room. The samples are dry. There is no natural convolution reverb baked in. This is a blessing, not a curse, because it allows the producer to place the orchestra in any virtual space—from a cathedral to a basement—using their own reverb plugins.
You should use orchestral essentials.sf2 if:
Tempo: 90 BPM Key: D Minor / D Major (Transition) Style: Epic Cinematic / Orchestral
This piece is designed to test the Strings (legato and staccato), Brass (sforzando), Woodwinds, and Percussion patches in your soundfont.