HTC Incredible :: Benefits Of Multi Tasking?

Can someone give me a real world, bare bones, idea of how the multitasking on the Incredible (android in general) actually works or what makes it so great? I know that is one of the things people haven't liked about the Iphone, and by default it is seen as a big benefit to android phones. I'm about to get my first smart phone and while I like the idea of multitasking, I'm wondering how many things can I actually run and/or use at one time. As I have thought about it, admittedly I'm not experienced, but I was thinking I could listen to music, while sending a text, or surfing the net, or maybe running some app, but how many things can I really do at once on the phone? Maybe while on a call I can be surfing the net or playing a game or running some app?

If I'm playing a game, won't that take up the whole screen, if I'm using it for navigation, I can't really be texting while it is guiding me, or making a call, I guess I could, but who knows? Hopefully this doesn't sound too stupid of a question, I'm just trying to figure out how I will best utilize my phone when I get it. Maybe the idea is that I don't have to close things out or have them close in order to do something else, and that allows me to go right back to what I was doing before I changed tasks? Any thoughts someone might have on this? Please keep in mind, this isn't a complaint or probing question as to limitations, I'm really just trying to figure out all the cool things I will be able to do with my phone when I get it.