2 Flats - A very advanced key signature.  The 3 sharps for beginners are gone.

Everything that was high 2nd is now low 2nd (F#, C# & G#)

Bb and Eb are low 1st on the D and A strings.

Not only is this hard to get the right fingerings but it's fast, really fast.  And everyone knows it or at least has heard it played well.