Quality of strings sound
One of the greatest deficiencies of MuseScore is sound quality or the strings, especially violins (violins are soul and backbone of orchestra!) (sic). They sound very unnatural, they have a disgusting kind of plastic echo, especially at heights. Sound of piano was greatly improved (older versions sounded like harpsichord) and clarinets too since version 2.0 (all winds are very well), but strings section showed no improvement at all. Each new version of MuseScore doesn’t improve violins, or strings in general, nor solo, nor ensemble.
Although even some payable VST software like Mixcraft or Sonar have bad strings (and music notation software like Finale), that is not apology.
I wonder why no-one till now complained about that main problem of MuseScore. I have composed few string quartets ("Piran" for instance) with present software, but the sound isn’t satisfying at all.