All Maul does is stand there and look menacing.
Here is a wild suggestion that someone should've thrown out there to Lucas while making TPM, actually have him do something evil! I mean, in the first 5 minutes of ANH you see Vader raid a diplomatic ship, killing countless soldiers, strangle Captain Antilles, and capture Leia. 30 minutes in the man has killed an entire tribe of Jawas and Luke's family. By half way point, he and his accomplice Tarkin have blown up a planet...THEY BLEW UP A ****ING PLANET
What does Maul do? Cross his arms? He is like the Dean Cain Superman for godsakes! Sure, he kills Qui-Gon, but it was a relatively fair fight (if anything he was being double teamed so how can you really hold it against him?)
Saying he is Sith isn't good enough. He looked so bad ass, but he did NOTHING AT ALL.
Lucas should've added a few scenes with him...for example on Tatioone instead of sending out droids to do his dirty work he should've maybe interrogated Shimi Skywalker or Watto as to where Qui-Gon went (and when I say interrogate, I mean Jack Bauer style). That alone would've made him ten times more feared and sinister.