Originally posted by Death55
They are used for accurate playing. It helps to make sure you play accuratly at whatever speed you want. Make sure you start off slow ;). I wouldnt say it is important when you first start playing guitar but it does come in handy when you do get a little better and especially when you want to shred lots. Without using a metronome you will probably just become really sloppy and miss lots of notes !
I think it is important when you start of playing, so you can form a good sense of rhythm. Why start off forming bad habits?!?