Inverter AC vs. Traditional Window Units: Which is actually worth it?

Hey everyone, can someone break down the actual difference between these new inverter AC units and the old models? Is it true they use significantly less power, or is it just marketing hype? Also, roughly how much extra am I looking at on my monthly electric bill during the winter if I stick with one of those older units? 🙂

I don't know, Alex1000, but you tell me—just what kind of technical issues are you actually having with this forum?