Here are the main points from Steve Reich's 3rd movement:

• The key is in E but the piece keeps the listener guessing right up until the bass guitar confirms by playing the note E at the end of it's two bar ostinato. It then changes to C minor. You can remember the key from the title: Electric Counterpoint, where the beginning letter shows the order of what the key is.
• Tonal ambiguity - keeping the key uncertain.
• The texture gradually builds up in layers and thins out towards the end.
• Piece concentrates on rhythmic development just as much as it does on melodic development.
• Changes metre is 3/2 (three minim beats in a bar) and occasionally changes to 12/8 (twelve quaver beats in a bar). 
• Rhythm is syncopated.
• The live guitar plays a resultant melody.
• Guitar 1 (first guitar you can hear at start) plays a one bar ostinato.
• There's a four part guitar canon on bars 1-23.
• Bass 1 and 2 introduced gradually, with their ostinatoes being built up.
• Use of panning - different instruments coming out of different speakers to create different textures.
• Live guitar introduces percussive texture chords which produces a strumming effect that cuts across rest of the parts.
• Shock to the system when key changes to C minor as it's unexpected.
• This piece has a rhythmic counterpoint being every part has a different rhythm and note.
• Unpredictable changes to key and time signature.
• Changing of keys become more frequent, building tension.
• Big crescendo at end to build tension.
• Structure is ABA with Coda at the end.