While you will hear many people suggesting betting exchanges have ruined online gambling the truth is that they have actually handed back more power to the punters and reduced the influence of the big bookmaking companies. In essence a betting exchange will cut out the middle man and see layers transacting with gamblers to make a market which offers up to 20% better prices for many sporting events.
The fact that many betting exchanges offer an in-play service also offers you the chance to place and lay bets as the event is ongoing. While there are many strategies to consider when in-play betting is added to the mix you need to remember that if you are watching for example a horse race on TV, the TV feed will be a few seconds behind the betting market.
Betting exchanges (such as Betfair) also offer a very interesting look at money flows for each participant in an event. In affect you can see the money coming in real time and you can see the odds moving real time. Gambling is a sport where money literally talks although you have to learn the language and exactly what it is telling you!