I'll tell you what it's not - it's the rubbish Honeywell guidance panel fitted to Embraers. It is without doubt the worst piece of avionics I have ever used. It's over complicated, has too much visual ambiguity, defaults to pointless values - God I hate it! If they made water I bet I wouldn't flow in a straight line, it also wouldn't be drinkable.
Best bit of avionics: Turn & Slip
Second Best: D/I slaved to remote compass
Most convenient: ACARS
Most useful system: ILS
PM